Spencerian Key to Practical Penmanship
Spencer, Platt Rogers
1873
lettering manualpenmanship
Artistic Signs: How to Design and Make Them
Koller, E.L.
1924
sign paintingsign making
Lettering Manuals & Alphabet Source Books
This list of vintage instructional lettering books is a work in progress. In the meantime, visit the old library.
To add:
https://pennavolans.com/bibliography/