From the about page:
International Joint Conferences on Artificial Intelligence is a non-profit corporation founded in California, in 1969 for scientific and educational purposes, including dissemination of information on Artificial Intelligence at conferences in which cutting-edge scientific results are presented and through dissemination of materials presented at these meetings in form of Proceedings, books, video recordings, and other educational materials. IJCAI conferences present premier international gatherings of AI researchers and practitioners. IJCAI conferences were held biennially in odd-numbered years since 1969. They are sponsored jointly by International Joint Conferences on Artificial Intelligence Organization (IJCAI), and the national AI societie(s) of the host nation(s).
While looking for a paper on automatic concept formulation for Jack Park, I found this archive of prior International Joint Conferences on Artificial Intelligence proceedings.
The latest proceedings, 2016, runs six volumes and approximately 4276 pages.
Enjoy!