|First Publication||1897? – Regensburg: Friedrich Pustet|
|Genre Categories||; ; ; ; ; ; ; ; ; ; ; ; ;; ; ;|
|Work Title||Missa Tertia|
|Opus/Catalogue NumberOp./Cat. No.||Op.7a|
|I-Catalogue NumberI-Cat. No.||IMH 4|
|First Publication.||1897? – Regensburg: Friedrich Pustet|
|Composer Time PeriodComp. Period||Romantic|
|Instrumentation||2 equal voices, organ|
It seems this might be a revision of Haller's Op.7 "Missa tertia (F) ad duas voces cum organo vel harmonio comitante" (published in 1876, per). The first occurrence of Op.7a appears as "Missa tertia f. vierstimmigen Männerchor eingerichtet v. P. Th. Marxer, Op. 3" per . A plate number of 990 would correspond to the mid to late 1890s.
Only one library listed in Worldcat (maybe more in KVK) has a copy of the 1876-published Missa tertia (as of 2014 August); there was another, 1885, edition published in the United States.
Indeed, many of his masses occur in multiple forms in HMB that seem to be revisions indicated by increasing letters. So yes, at a guess, Mass No.3 is actually Op.7 published in 1876 and this should appear under that page (if we can confirm that they -are- the same work modulo revision, again...)