TY  - JOUR
AU  - Ronald Brown
TI  - Groupoids and crossed objects in algebraic topology
JO  - Homology, homotopy, and applications
PY  - 1999
SP  - 1
EP  - 78
VL  - 1
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/articles/10.4310/HHA.1999.v1.n1.a1/
DO  - 10.4310/HHA.1999.v1.n1.a1
LA  - en
ID  - HHA_1999_1_1_a1
ER  -