Standard DIN 1304-1, Publication date: 1994-03 Letter symbols for physical quantities; symbols for general use

Standard DIN 1304-6, Publication date: 1992-05 Letter symbols for physical quantities; symbols to be used in electrical communication technology

IEC 49/503/CDV, Publication date: 2001-04 Letter symbols for physical quantities; symbols to be used in electrical communication technology

Standard IEC 60027-2, Publication date: 2000-11 Letter symbols to be used in electrical technology - Part 2 : Telecommunications and electronics

Standard IEC 60050-561, Publication date: 1991-11 International electrotechnical vocabulary; chapter 561: piezoelectric devices for frequency control and selection

IEC 61178-1, Publication date: 1993-03 International electrotechnical vocabulary; chapter 561: piezoelectric devices for frequency control and selection