TY - RPRT TI - Mean electron density variations of the quiet ionosphere no. 8 AU - Brown, DJ AU - Wescott, LR AU - Wright, J W PY - 1959 PB - National Bureau of Standards CY - Gaithersburg, MD SN - NBS TN 40-8 DO - 10.6028/NBS.TN.40-8 ER -