More new volumes

Thanks to Google Books, I’ve been able to continue to index a lot of material without having to scan it myself. I’ve added about 6 more volumes in the last few days, for a total number of source volumes on the site exceeding 50. (Including at least 2000 songs)

As resources are available, I will begin seeking out more high quality sources to scan, and focusing more on the repertoire most needed. (Noting that several volumes are now available from Google that I had laboriously scanned myself!)