 From c. 1522, he was employed by his order to write a chronicle about the Franciscans in Scandinavia.After the Reformation (in 1537) the order was dissolved in Denmark, but Petrus continued his work on Danish history until c. 1560, as Danorum Gesta.The manuscript of "Collectanea ad historiam danicam pertinentia" (AM 107 8°, 172 folia) is a notebook with complicated structure, extended by numerous extra pages and loose slips of paper, and numerous interlinear and marginal notes, and has never been edited in its entirety.