Radio, Jan 1939, p. 176. (not specifically called the U-10, probably one version earlier based on slight differences in appearance.)
Radio News, Feb 1939, p. 49. (designed by McMurdo Silver)
QST, Sep 1939, p. 98. (The U-10 is mentioned in this ad, but I saw no previous as for it.)
Lafayette catalog number 78, p. 146.
References
Technical description. Radio News, Feb 1939, p. 37.
