The posthumously published collection of eight sacred motets for solo voice and one or two instruments did not get preserved in its complete form. However, it can be reconstructed from several preserved handwritten copies whose confrontation reveals various versions of the compositions, as well as other alterations and corrections made by the copyists. The editor thus faces the question which of the available sources to consider as the primary one. The study aims at presenting the current state of the sources which form the basis of the study of this collection and, at the same time, at pointing to the specific cases of problems and their solutions. Several procedures are generally applied in the case of the urtext editions of other collections of 17th-century music, which may serve as practical examples, analogies, or starting points for us.