TY  - JOUR
AU  - Harry A.W.M. Kneppers
TI  - Two-dimensional formal groups: from isomorphism to isogeny.
JO  - Mathematische Zeitschrift
PY  - 1990
SP  - 309
EP  - 314
VL  - 205
IS  - 3
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MZ_1990__205_3_174176/
ID  - MZ_1990__205_3_174176
ER  -