1. Bonikowski Z. (2010) Unit operations in approximation spaces. In: Szczuka M., Kryszkiewicz M., Ramanna S., Jensen R. (eds). Rough Sets and Current Trends in Computing LNAI, vol 6086. Springer, Berlin, pp 337–346
2. Bonikowski, Z., Wybraniec-Skardowska, U.: A generalization of certain set-theoretical operations. In: Beziau, J.-Y., Caleiro, C., Costa-Leite, A., Ramos, J. (eds.) UniLog 2010, Book of Abstracts, World Congress and School on Universal Logic (3rd edition), April 18–25, 2010, Monte Estoril, Portugal. Instituto Superior Tecnico, Departamento de Matematica, p. 59 (2010)
3. Borkowski, L.: Logika Formalna. PWN, Warszawa (1970) (English translation: Formal Logic, Akademie-Verlag, Berlin (1977))
4. Bryll, G.: Kilka uzupełnień teorii zdań odrzuconych (Some supplements of the theory of rejected propositions). In: [45], 133–154 (1969)
5. Bryll, G.: Zwia̧zki logiczne pomiȩdzy zdaniami nauk empirycznych (Logical relations between sentences of empirical sciences). In: [45], 155–216 (1969)