1. Weak (B, N)-pairs of rank 2;Delgado,1985
2. Failure of factorization and primitive amalgams of index (3, 3);Chermak;Comm. in Algebra,1986
3. Some parabolic systems of rank 2 related to sporadic groups;Jianhua;J. Algebra,1986
4. W. Lempken, C. Parker, and P. Rowley, (S3, S6)-amalgams, I, II, III, IV, V, VI, manuscripts.