TY - RPRT TI - Circular of the Bureau of Standards no. 49 2nd edition: safety rules to be observed in the operation and maintenance of electrical equipment and lines PY - 1915 PB - National Bureau of Standards CY - Gaithersburg, MD SN - NBS CIRC 49e2 DO - 10.6028/NBS.CIRC.49e2 ER -