Jan-Willem Neurdenburg, Phil S. Schwarz. ≅USER: the user-definable system function in Data General's AOS/VS APL. In Jerry R. Turner, editor, Proceedings of the international conference on APL - APL and the future, APL 1985, Seattle, Washington, USA, May 12-16, 1985. pages 299-307, ACM, 1985. [doi]
Abstract is missing.