TITLE: Dieudonné theory over non-perfect base fields
QUESTION [7 upvotes]: Is there a Dieudonné theory for $p$-divisible groups (or for finite flat group schemes of $p$-power order) over non-perfect base-fields?

REPLY [6 votes]: Johan de Jong sent me an e-mail with a reference to Jong, A.J. de. "Finite locally free group schemes in characteristic $p$ and Dieudonné modules" Inventiones mathematicae 114.1 (1993): 89-138. https://eudml.org/doc/144143.