Authors: Tamanoi, Hirotaka
Superior Title: Transactions of the American Mathematical Society, 2000 Nov 01. 352(11), 5139-5178.
Access URL: https://www.jstor.org/stable/221929
Authors: Fleury, Patrick J.
Superior Title: Proceedings of the American Mathematical Society, 1971 Nov 01. 30(3), 405-411.
Access URL: https://www.jstor.org/stable/2037706
Authors: Macias-Virgós, Enrique
Superior Title: Transactions of the American Mathematical Society, 1994 Aug 01. 344(2), 701-711.
Access URL: https://www.jstor.org/stable/2154502