@article{1178207479,
author = {Sekiguchi, Tsutomu and Suwa, Noriyuki},
title = {A note on extensions of algebraic and formal groups, IV. Kummer-Artin-Schreier-Witt theory of degree $p^2$},
journal = {Tohoku Math. J. (2)},
volume = {53},
number = {4},
year = {2001},
pages = { 203-240},
language = {en},
url = {http://dml.mathdoc.fr/item/1178207479}
}
Sekiguchi, Tsutomu; Suwa, Noriyuki. A note on extensions of algebraic and formal groups, IV. Kummer-Artin-Schreier-Witt theory of degree $p^2$. Tohoku Math. J. (2), Tome 53 (2001) no. 4, pp. 203-240. http://gdmltest.u-ga.fr/item/1178207479/