Меловой период

Peryt, D., Dubicka, Z., 2015. Foraminiferal bioevents in the Upper Campanian to lowest Maastrichtian of the Middle Vistula River section, Poland // Geological Quarterly, 59 (4), doi: 10.7306/gq.1252

https://gq.pgi.gov.pl/article/download/24064/pdf_1248