Aiken, Alexander, Dexter Kozen, and Ed Wimmers. ‚ÄúDecidability of Systems of Set Constraints With Negative Constraints‚ÄĚ. BRICS Report Series 1, no. 32 (October 31, 1994). Accessed October 18, 2019. https://tidsskrift.dk/brics/article/view/21611.