TY  - JOUR
AU  - Rival, Ivan
AU  - Sands, Bill
TI  - Planar Sublattices of a Free Lattice. I
JO  - Canadian journal of mathematics
PY  - 1978
SP  - 1256
EP  - 1283
VL  - 30
IS  - 6
UR  - http://geodesic.mathdoc.fr/articles/10.4153/CJM-1978-104-2/
DO  - 10.4153/CJM-1978-104-2
ID  - 10_4153_CJM_1978_104_2
ER  -