TY - RPRT TI - Circular of the Bureau of Standards no. 22: standard specifications for transformers, oil-immersed, self-cooled, 60-cycle, 2200 volts PY - 1910 PB - National Bureau of Standards CY - Gaithersburg, MD SN - NBS CIRC 22 DO - 10.6028/NBS.CIRC.22 ER -