IEEE/ANSI 315-1971 IEEE Standard and American National Standard for Electrical and Electronics Diagrams (Including Reference Designation class Designation Letters)
1970IEEE/ANSI 315-1975 IEEE Standard for Graphic Symbols for Electrical and Electronics Diagrams (Including Reference Designation Letters)
1970IEEE/ANSI 315-1971 IEEE Standard and American National Standard for Electrical and Electronics Diagrams (Including Reference Designation class Designation Letters)