@article{GDZPPN002199602,
title = {On formal groups over complete discrete valuation rings with application to a theorem of Lutz.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {334},
year = {1982},
pages = {79-90},
zbl = {0478.14036},
url = {http://dml.mathdoc.fr/item/GDZPPN002199602}
}
Oshikawa, Keiichi. On formal groups over complete discrete valuation rings with application to a theorem of Lutz.. Journal für die reine und angewandte Mathematik, Tome 334 (1982) pp. 79-90. http://gdmltest.u-ga.fr/item/GDZPPN002199602/