Free public domain sheet music from IMSLP / Petrucci Music Library
||The Messenger of Song
||The Messenger of Song contains a graded course for singing classes and day schools also solos, duetts, quartetts, glees and choruses for musical conventions, musical institutes, etc., etc. by J.H. Hall, J.H. Ruebush and E.T. Hildebrand
||voices (various 2-4), some pieces with piano/keyboard accompaniment
Aikin 7-shape notation.