Compositio Mathematica, Volume 40 (1980) no. 1, pp. 69-78.

McGovern, William M.

Compositio Mathematica, Volume 101 (1996) no. 1, pp. 77-98.

Garfinkle, Devra

Compositio Mathematica, Volume 88 (1993) no. 2, pp. 187-234.

Garfinkle, Devra

Compositio Mathematica, Volume 81 (1992) no. 3, pp. 307-336.

Garfinkle, Devra

Compositio Mathematica, Volume 75 (1990) no. 2, pp. 135-169.

Matumoto, Hisayosi

C^{- \infty}

Annales scientifiques de l'École Normale Supérieure, Serie 4, Volume 23 (1990) no. 2, pp. 311-367.

Joseph, A.

Compositio Mathematica, Volume 42 (1980) no. 1, pp. 23-30.