Book Sales Catalogues Online offers a comprehensive bibliography of book sales catalogues printed in the Dutch Republic before 1801, providing full access to some 4,000 digital facsimiles from ca. 50 libraries across Europe. These catalogues are a key primary source for research on the history of the book and libraries, the history of ideas, the history of collecting, the history of literature, and the history of art. The catalogues contain information on books from all over Europe in various languages, such as Dutch, French, and Latin.

The Digital Library of the Catholic Reformation makes the documentary riches of this era accessible, adding functionalities that maximize the flexibility with which researchers can search, view, organize, and manipulate this historically important source material. With new content uploads occurring on a regular basis, the database offers a constantly growing treasury of documents, including papal and synodal decrees, catechisms and inquisitorial manuals, biblical commentaries, theological treatises and systems, liturgical writings, saints' lives, and devotional works.

The Digital Library of Classic Protestant Texts gives researchers access to an extensive range of seminal works from the Reformation and post-Reformation eras. With new content uploads occurring on a regular basis, the database offers a constantly growing treasury of theological writings, biblical commentaries, confessional documents, and polemical treatises written by more than 300 Protestant authors.

The database OLC Ibero-America, Spain and Portugal is a regional related section from the Online Contents database that is constantly being completed with the addition of selected journals from the competent Libraries, the Library of the Ibero-American Institute Prussian Cultural Heritage (Ibero-America and the Caribbean) and the state and university library SUB Hamburg (Spain and Portugal). Currently more than 1.400 journals are being indexed. Gradually earlier editions of these journals will also be made accessible.

Based on the digitization of K. G. Saur's Biographical Archives, WBIS Online provides biographical information on over 6 Million people from the 8th century B.C. to the present as well as from all countries and regions worldwide. The subscription covers all biographical archives, except the German Biographical Archive, DBA.