1. Azem S., Allison B., Berman S., Gao Y. and Pianzola A. (1997). Extended affine Lie algebras and their root systems. Mem. Am. Math. Soc. 603: 128
2. Allison B.N., Berman S. and Pianzola A. (2004). Covering algebras II: Isomorphism of loop algebras. J Reine Angew. Math. 571: 39–71
3. Allison B.N., Berman S. and Pianzola A. (2006). Iterated loop algebras. Pacific J. Math. 227: 1–42
4. Allison, B.N., Berman, S., Pianzola, A.: Covering algebras III (in preparation)
5. Allison, B., Berman, S., Faulkner, J., Pianzola, A.: Realization of graded-simple algebras as loop algebras. Forum Math. (2007) (in press)