TY - RPRT TI - Letter Circular 185: specifications for portable frequency meter for frequencies from 1500 to 15000 kilocycles, Bureau of Standards type K PY - 1926 PB - National Institute of Standards and Technology CY - Gaithersburg, MD SN - LCIRC 185r1926 DO - 10.6028/NBS.LCIRC.185r1926 ER -