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Author |
Debora Gil; Petia Radeva |
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Title |
Curvature Vector Flow to Assure Convergent Deformable Models for Shape Modelling |
Type |
Book Chapter |
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Year |
2003 |
Publication |
Energy Minimization Methods In Computer Vision And Pattern Recognition |
Abbreviated Journal |
LNCS |
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Volume |
2683 |
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Pages |
357-372 |
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Keywords |
Initial condition; Convex shape; Non convex analysis; Increase; Segmentation; Gradient; Standard; Standards; Concave shape; Flow models; Tracking; Edge detection; Curvature |
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Abstract |
Poor convergence to concave shapes is a main limitation of snakes as a standard segmentation and shape modelling technique. The gradient of the external energy of the snake represents a force that pushes the snake into concave regions, as its internal energy increases when new inexion points are created. In spite of the improvement of the external energy by the gradient vector ow technique, highly non convex shapes can not be obtained, yet. In the present paper, we develop a new external energy based on the geometry of the curve to be modelled. By tracking back the deformation of a curve that evolves by minimum curvature ow, we construct a distance map that encapsulates the natural way of adapting to non convex shapes. The gradient of this map, which we call curvature vector ow (CVF), is capable of attracting a snake towards any contour, whatever its geometry. Our experiments show that, any initial snake condition converges to the curve to be modelled in optimal time. |
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Publisher |
Springer, Berlin |
Place of Publication |
Lisbon, PORTUGAL |
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Springer, B. |
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Series Title |
Lecture Notes in Computer Science |
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LNCS |
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ISSN |
0302-9743 |
ISBN |
3-540-40498-8 |
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IAM;MILAB |
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no |
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Call Number |
IAM @ iam @ GIR2003b |
Serial |
1535 |
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Author |
Debora Gil |
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Title |
Geometric Differential Operators for Shape Modelling |
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Book Whole |
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Year |
2004 |
Publication |
PhD Thesis, Universitat Autonoma de Barcelona-CVC |
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Medical imaging feeds research in many computer vision and image processing fields: image filtering, segmentation, shape recovery, registration, retrieval and pattern matching. Because of their low contrast changes and large variety of artifacts and noise, medical imaging processing techniques relying on an analysis of the geometry of image level sets rather than on intensity values result in more robust treatment. From the starting point of treatment of intravascular images, this PhD thesis ad- dresses the design of differential image operators based on geometric principles for a robust shape modelling and restoration. Among all fields applying shape recovery, we approach filtering and segmentation of image objects. For a successful use in real images, the segmentation process should go through three stages: noise removing, shape modelling and shape recovery. This PhD addresses all three topics, but for the sake of algorithms as automated as possible, techniques for image processing will be designed to satisfy three main principles: a) convergence of the iterative schemes to non-trivial states avoiding image degeneration to a constant image and representing smooth models of the originals; b) smooth asymptotic behav- ior ensuring stabilization of the iterative process; c) fixed parameter values ensuring equal (domain free) performance of the algorithms whatever initial images/shapes. Our geometric approach to the generic equations that model the different processes approached enables defining techniques satisfying all the former requirements. First, we introduce a new curvature-based geometric flow for image filtering achieving a good compromise between noise removing and resemblance to original images. Sec- ond, we describe a new family of diffusion operators that restrict their scope to image level curves and serve to restore smooth closed models from unconnected sets of points. Finally, we design a regularization of snake (distance) maps that ensures its smooth convergence towards any closed shape. Experiments show that performance of the techniques proposed overpasses that of state-of-the-art algorithms. |
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Thesis |
Ph.D. thesis |
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Publisher |
Ediciones Graficas Rey |
Place of Publication |
Barcelona (Spain) |
Editor |
Jordi Saludes i Closa;Petia Radeva |
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ISBN |
84-933652-0-3 |
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prit |
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Notes |
IAM; |
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no |
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Call Number |
IAM @ iam @ GIL2004 |
Serial |
1517 |
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Author |
Debora Gil; Petia Radeva |
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Title |
Inhibition of False Landmarks |
Type |
Book Chapter |
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Year |
2004 |
Publication |
Recent Advances in Artificial Intelligence Research and Development |
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Pages |
233-244 |
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Abstract |
We argue that a corner detector should be based on the degree of continuity of the tangent vector to the image level sets, work on the image domain and need no assumptions on neither the image local structure nor the particular geometry of the corner/junction. An operator measuring the degree of differentiability of the projection matrix on the image gradient fulfills the above requirements. Its high sensitivity to changes in vector directions makes it suitable for landmark location in real images prone to need smoothing to reduce the impact of noise. Because using smoothing kernels leads to corner misplacement, we suggest an alternative fake response remover based on the receptive field inhibition of spurious details. The combination of both orientation discontinuity detection and noise inhibition produce our Inhibition Orientation Energy (IOE) landmark locator. |
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Publisher |
IOS Press |
Place of Publication |
Barcelona (Spain) |
Editor |
al, J.V. et |
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Notes |
IAM;MILAB |
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no |
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Call Number |
IAM @ iam @ GiR2004a |
Serial |
1533 |
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Author |
Fernando Vilariño; Debora Gil; Petia Radeva |
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Title |
A Novel FLDA Formulation for Numerical Stability Analysis |
Type |
Book Chapter |
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Year |
2004 |
Publication |
Recent Advances in Artificial Intelligence Research and Development |
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Volume |
113 |
Issue |
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Pages |
77-84 |
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Keywords |
Supervised Learning; Linear Discriminant Analysis; Numerical Stability; Computer Vision |
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Abstract |
Fisher Linear Discriminant Analysis (FLDA) is one of the most popular techniques used in classification applying dimensional reduction. The numerical scheme involves the inversion of the within-class scatter matrix, which makes FLDA potentially ill-conditioned when it becomes singular. In this paper we present a novel explicit formulation of FLDA in terms of the eccentricity ratio and eigenvector orientations of the within-class scatter matrix. An analysis of this function will characterize those situations where FLDA response is not reliable because of numerical instability. This can solve common situations of poor classification performance in computer vision. |
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IOS Press |
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Editor |
J. Vitrià, P. Radeva and I. Aguiló |
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ISBN |
978-1-58603-466-5 |
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Notes |
MV;IAM;MILAB;SIAI |
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no |
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Call Number |
IAM @ iam @ VGR2004 |
Serial |
1663 |
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Permanent link to this record |
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Author |
Misael Rosales; Petia Radeva; Oriol Rodriguez; Debora Gil |
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Title |
Suppression of IVUS Image Rotation. A Kinematic Approach |
Type |
Book Chapter |
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Year |
2005 |
Publication |
Functional Imaging and Modeling of the Heart |
Abbreviated Journal |
LNCS |
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Volume |
3504 |
Issue |
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Pages |
889-892 |
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Abstract |
IntraVascular Ultrasound (IVUS) is an exploratory technique used in interventional procedures that shows cross section images of arteries and provides qualitative information about the causes and severity of the arterial lumen narrowing. Cross section analysis as well as visualization of plaque extension in a vessel segment during the catheter imaging pullback are the technique main advantages. However, IVUS sequence exhibits a periodic rotation artifact that makes difficult the longitudinal lesion inspection and hinders any segmentation algorithm. In this paper we propose a new kinematic method to estimate and remove the image rotation of IVUS images sequences. Results on several IVUS sequences show good results and prompt some of the clinical applications to vessel dynamics study, and relation to vessel pathology. |
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Publisher |
Springer Berlin / Heidelberg |
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Editor |
Frangi, Alejandro and Radeva, Petia and Santos, Andres and Hernandez, Monica |
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Series Editor |
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Series Title |
Lecture Notes in Computer Science |
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LNCS |
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Series Volume |
3504 |
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Notes |
IAM;MILAB |
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no |
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Call Number |
IAM @ iam @ RRR2005 |
Serial |
1645 |
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Author |
Debora Gil; Jordi Gonzalez; Gemma Sanchez (eds) |
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Title |
Computer Vision: Advances in Research and Development |
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Book Whole |
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Year |
2007 |
Publication |
Proceedings of the 2nd CVC International Workshop |
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Publisher |
UAB |
Place of Publication |
Bellaterra (Spain) |
Editor |
Debora Gil; Jordi Gonzalez; Gemma Sanchez |
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2 |
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ISBN |
978-84-935251-4-9 |
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Notes |
IAM; ISE; DAG |
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no |
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Call Number |
IAM @ iam @ GGS2007 |
Serial |
1493 |
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Author |
Debora Gil; Oriol Rodriguez-Leor; Petia Radeva; Aura Hernandez-Sabate |
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Title |
Assessing Artery Motion Compensation in IVUS |
Type |
Book Chapter |
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Year |
2007 |
Publication |
Computer Analysis Of Images And Patterns |
Abbreviated Journal |
LNCS |
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Volume |
4673 |
Issue |
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Pages |
213-220 |
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Keywords |
validation standards; quality measures; IVUS motion compensation; conservation laws; Fourier development |
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Abstract |
Cardiac dynamics suppression is a main issue for visual improvement and computation of tissue mechanical properties in IntraVascular UltraSound (IVUS). Although in recent times several motion compensation techniques have arisen, there is a lack of objective evaluation of motion reduction in in vivo pullbacks. We consider that the assessment protocol deserves special attention for the sake of a clinical applicability as reliable as possible. Our work focuses on defining a quality measure and a validation protocol assessing IVUS motion compensation. On the grounds of continuum mechanics laws we introduce a novel score measuring motion reduction in in vivo sequences. Synthetic experiments validate the proposed score as measure of motion parameters accuracy; while results in in vivo pullbacks show its reliability in clinical cases. |
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Springerlink |
Place of Publication |
Heidelberg |
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Lecture Notes in Computer Science |
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ISBN |
978-3-540-74271-5 |
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Notes |
IAM;MILAB |
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no |
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Call Number |
IAM @ iam @ GRR2007 |
Serial |
1540 |
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Author |
Jaume Garcia; Debora Gil; Aura Hernandez-Sabate |
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Title |
Endowing Canonical Geometries to Cardiac Structures |
Type |
Book Chapter |
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Year |
2010 |
Publication |
Statistical Atlases And Computational Models Of The Heart |
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Volume |
6364 |
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Pages |
124-133 |
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Abstract |
International conference on Cardiac electrophysiological simulation challenge
In this paper, we show that canonical (shape-based) geometries can be endowed to cardiac structures using tubular coordinates defined over their medial axis. We give an analytic formulation of these geometries by means of B-Splines. Since B-Splines present vector space structure PCA can be applied to their control points and statistical models relating boundaries and the interior of the anatomical structures can be derived. We demonstrate the applicability in two cardiac structures, the 3D Left Ventricular volume, and the 2D Left-Right ventricle set in 2D Short Axis view. |
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Springer Berlin / Heidelberg |
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Editor |
Camara, O.; Pop, M.; Rhode, K.; Sermesant, M.; Smith, N.; Young, A. |
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Lecture Notes in Computer Science |
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LNCS |
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IAM |
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Call Number |
IAM @ iam @ GGH2010b |
Serial |
1515 |
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Author |
Aura Hernandez-Sabate; Debora Gil |
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Title |
The Benefits of IVUS Dynamics for Retrieving Stable Models of Arteries |
Type |
Book Chapter |
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Year |
2012 |
Publication |
Intravascular Ultrasound |
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
185-206 |
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Publisher |
Intech |
Place of Publication |
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Editor |
Yasuhiro Honda |
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Language |
English |
Summary Language |
english |
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ISBN |
978-953-307-900-4 |
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Notes |
IAM; ADAS |
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no |
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Call Number |
IAM @ iam @ HeG2012 |
Serial |
1684 |
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Author |
Sergio Vera; Debora Gil; Agnes Borras; F. Javier Sanchez; Frederic Perez; Marius G. Linguraru; Miguel Angel Gonzalez Ballester |
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Title |
Computation and Evaluation of Medial Surfaces for Shape Representation of Abdominal Organs |
Type |
Book Chapter |
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Year |
2012 |
Publication |
Workshop on Computational and Clinical Applications in Abdominal Imaging |
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Volume |
7029 |
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Pages |
223–230 |
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Keywords |
medial manifolds, abdomen. |
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Abstract |
Medial representations are powerful tools for describing and parameterizing the volumetric shape of anatomical structures. Existing methods show excellent results when applied to 2D
objects, but their quality drops across dimensions. This paper contributes to the computation of medial manifolds in two aspects. First, we provide a standard scheme for the computation of medial
manifolds that avoid degenerated medial axis segments; second, we introduce an energy based method which performs independently of the dimension. We evaluate quantitatively the performance of our
method with respect to existing approaches, by applying them to synthetic shapes of known medial geometry. Finally, we show results on shape representation of multiple abdominal organs,
exploring the use of medial manifolds for the representation of multi-organ relations. |
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Address |
Toronto; Canada; |
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Publisher |
Springer Link |
Place of Publication |
Berlin |
Editor |
H. Yoshida et al |
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Language |
English |
Summary Language |
English |
Original Title |
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Series Editor |
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Series Title |
Lecture Notes in Computer Science |
Abbreviated Series Title |
LNCS |
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ISSN |
0302-9743 |
ISBN |
978-3-642-28556-1 |
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ABDI |
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Notes |
IAM;MV |
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no |
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Call Number |
IAM @ iam @ VGB2012 |
Serial |
1834 |
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