Weidenbach, Christoph Automation of Logic, MPI for Informatics, Max Planck Society; Programming Logics, MPI for Informatics, Max Planck Society;
https://rdcu.be/dvw0t (Publisher version)
Weidenbach, C. (1997). SPASS Version 0.49. Journal of Automated Reasoning, 18(2), 247-252. doi:10.1023/A:1005812220011.