@article{DOCMA_2002__7__a11,
     author = {Oort, Frans and Zink, Thomas},
     title = {Families of $p$-divisible groups with constant {Newton} polygon},
     journal = {Documenta mathematica},
     pages = {183--201},
     publisher = {mathdoc},
     volume = {7},
     year = {2002},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/DOCMA_2002__7__a11/}
}