Paul Welsch kept a catalog of his painted work from 1915 to the beginning of 1929. This document gives precious indications for the dating of the oils, some of which, as he annotated in red pencil, have been photographed in black and white. Note, however, that this catalog is selective: it only takes into account the signed canvases (some, however, are omitted) and neglects those that it should have considered as drafts of the final canvas. It is also likely that Paul Welsch did not keep this catalog from day to day but listed certain periods later, which would explain the omissions (especially before the 1920s).