IN 1949, Standards on Piezoelectric Crystals [ l ] were issued covering the definition of axes for piezoelectric crystals and their relation to rectangular axes, standards for specifying crystal plate orientation and nomenclature referring to the piezoelectric relations, symbols, and units. In 1957, the IRE Standards on Piezoelectric Crystals [2 ] was issued covering the piezoelectric vibrator: definition and measurements. It is the object of these present Standards to specify a method for determining the basic elastic, piezoelectric, and dielectric constants of crystals.