Manuscripts from the abandoned library of the Premonstratensian Abbey of St Peter at Weißenau near Ravensburg are currently held in many European and American libraries. After the abbey was secularised in 1802 the library the Counts of von Sternberg-Manderscheid tool possession of it and after 1830 it was incorporated into the Prague palace library of the House of Lobkowicz, with which it was transferred in 1928 to what i snow the National Library of the Czecgh Republic. The manuscript collection of Prague Lobkowicz Library (shelf mark XXIII) contains almost a half of the extant Weißenau collection numbering circa 90 codices. The study delivers the results of systematic research into ownership notes in this file that uncovered fragments of several interesting private libraries of the fifteenth and sixteenth century from the territory of the Constance Diocese.