TY  - JOUR
AU  - Dumir, V. C.
AU  - Hans-Gill, R. J.
AU  - Wilker, J. B.
TI  - Contributions to a General Theory of View-Obstruction Problems
JO  - Canadian journal of mathematics
PY  - 1993
SP  - 517
EP  - 536
VL  - 45
IS  - 3
UR  - http://geodesic.mathdoc.fr/articles/10.4153/CJM-1993-027-9/
DO  - 10.4153/CJM-1993-027-9
ID  - 10_4153_CJM_1993_027_9
ER  -