In February 1992, T Ivanovic, working with the author in the archives at Kazan University, discovered new material relating to the life and work of the logician P S Poretsky (1846-1907).
Noong Pebrero 1992, T Ivanovic, nagtatrabaho sa may-akda sa mga archives at Kazan University, natuklasan ng bagong materyal na may kaugnayan sa buhay at gawain ng mga logician PS Poretsky (1846-1907).