Question about Dotzauer catalogue source

[NotationMaster]

Dear all,

I would like to know if possible the source used by the person(s) who compiled the Dotzauer list of works https://imslp.org/wiki/List_of_works_by ... h_Dotzauer

Both op. 16 and op. 44 are given as cello duets but the libraries holding those items only have them marked as violin duets.
It would be really helpful if someone could post here where the cello versions were found as it is certainly possible that Dotzauer himself arranged them for two cellos (before or after the violin version).

Thanks

NM