TY  - JOUR
AU  - Walker, Marshall
TI  - Homotopy Pull-Backs and Applications to Duality
JO  - Canadian journal of mathematics
PY  - 1977
SP  - 45
EP  - 64
VL  - 29
IS  - 1
UR  - http://geodesic.mathdoc.fr/articles/10.4153/CJM-1977-004-3/
DO  - 10.4153/CJM-1977-004-3
ID  - 10_4153_CJM_1977_004_3
ER  -