@article{01545112, title = {Newton polygons and formal groups: Conjectures by Manin and Grothendieck.}, journal = {Annals of Mathematics. Second Series}, volume = {151}, year = {2000}, pages = {183-206}, doi = {10.2307/2661381}, zbl = {0991.14016}, language = {en}, url = {http://dml.mathdoc.fr/item/01545112} }
Oort, Frans. Newton polygons and formal groups: Conjectures by Manin and Grothendieck.. Annals of Mathematics. Second Series, Tome 151 (2000) pp. 183-206. doi : 10.2307/2661381. http://gdmltest.u-ga.fr/item/01545112/