A. Pietrowski

发表

A. Karrass, D. Solitar, A. Pietrowski, 1974, Canadian Journal of Mathematics.

A. Pietrowski, J. McCool, 1973 .

M. J. Dunwoody, A. Pietrowski, 1973, Canadian Mathematical Bulletin.

A. Karrass, D. Solitar, A. Karrass, 1973, Journal of the Australian Mathematical Society.