TY - RPRT TI - Circular of the Bureau of Standards no. 502: bibliography of electron microscopy AU - Marton, Claire AU - Swerdlow, Max AU - VanBronkhorst, Alan AU - Meryman, Harold PY - 1950 PB - National Bureau of Standards CY - Gaithersburg, MD SN - NBS CIRC 502 DO - 10.6028/NBS.CIRC.502 ER -