M. N. Beitman Supreme Publications Service Manuals

Beitman Supreme Radio Diagrams were annual volumes with service details and schematics of consumer radios and later TV and appliances.
Morris Beitman, a Chicagoan with US Army Signal Corps technician training, first taught in local schools and then began publishing comprehensive radio reference materials.
I came across these on the great World Radio History Website after I was given a couple of old Radios and I have found these really useful.