https://www.dbc.wroc.pl/dlibra
Lower Silesian Digital Library (DBC) is an online library which provides electronic versions of readers, text books, journals, special collection and dissertations stored in the libraries of the institutions which are united within a Consortium of Dolnoslaska Digital Library.
Digital Libraries Federation (Federacja Bibliotek Cyfrowych, FBC) is a search engine that brings together digital libraries, museums, archives and repositories. The mission of FBC is to make available and promote Polish cultural and scientific achievements.
Periodika aus den Sammlungen polnischer kultureller und wissenschaftlicher Einrichtungen.
The State Archives form a network consisting of 3 central archives located in Warsaw and 30 regional archives with their branches
https://jbc.bj.uj.edu.pl/dlibra
Digitale Sammlung der Uniwersytet Jagielloński in Krakau.