P. Gehring, and R. Wille. Proceedings of the 14th International Conference on Conceptual Structures (ICCS 2006), volume 4068 of Lecture Notes in Computer Science, page 215-228. Springer, (2006)
S. Masmoudi. Proceedings of the 9th International Conference on Conceptual Structures (ICCS 2001), volume 2120 of Lecture Notes in Computer Science, page 58-71. Springer, (2001)
F. Arzarello. the 24th Conference of the International Group for the Psychology of Mathematics Education (PME), 1, page 23--38. Hiroshima, Japan, (2000)
G. Mineau, G. Stumme, and R. Wille. Conceptual Structures: Standards and Practices. Proc. ICCS '99, volume 1640 of LNAI, page 423-441. Heidelberg, Springer, (1999)
D. Jonassen, K. Beissner, and M. Yacci. LEA. Lawrence Erlbaum Associates, Hillsdale, NJ, (1993)David H. Jonassen, Katherine Beissner, Michael Yacci. Includes bibliographical
references and index. $5GBV.