E. Shapiro. Proceedings of the 7th International Joint Conference on Artificial Intelligence (IJCAI '81), стр. 446--451. Los Altos, CA, Morgan Kaufmann, (1981)
E. Meijer, M. Fokkinga, и R. Paterson. Proceedings of the 5th ACM Conference on Functional Programming Languages and Computer Architecture (FPCA'91), стр. 124--144. Springer Verlag, (1991)