BS 9612 N013:1979
用于振荡器应用的冷焊密封石英晶体单元的详细规范 DK 外壳 频率范围为 25 至 75 MHz 第三泛音厚度剪切模式 AT 切割 适用于窄温度范围内的操作（温度控制）...
Detail specification for cold welded seal quartz crystal units for oscillator applications. DK enclosure, 25 to 75 MHz frequency range. Third overtone thickness-shear mode, AT-cut, for operation over narrow temperature ranges (temperature controlled). ...