According to http://www.rootsandrhythm.com/roots/New_Releases/newsletter124_country.htm, "Back in the Old Sunday School," performed by The Fabulous Beverly Hill Billies, is included in the Various Artists' collection "Traditional Country Music Makers, Vol. 8: The Gospel Way," Magnet #MRCD008, and the CD can be purchased from that web site.

And according to http://www.millersville.edu/~archives/archweb/manuscripts/scoreB.htm+%22Back+in+the+Old+Sunday+School%22&hl=en&ie=UTF-8, the authors were Phillips H. Lord, May Singhi Breen and Peter De Rose, and it was published as sheet music in 1932.