Construction of some classes in the cohomology of Siegel modular threefolds

Nygaard, Niels O.

Compositio Mathematica, Volume 97 (1995) p. 173-186

Slopes of powers of Frobenius on crystalline cohomology

Nygaard, Niels O.

Annales scientifiques de l'École Normale Supérieure, Volume 14 (1981) p. 369-401

Higher de Rham-Witt complexes of supersingular $K3$ surfaces

Nygaard, Niels O.

Compositio Mathematica, Volume 42 (1980) p. 245-271

Closedness of regular $1$-forms on algebraic surfaces

Nygaard, Niels O.

Annales scientifiques de l'École Normale Supérieure, Volume 12 (1979) p. 33-45