1. Chapman, S., , and J., Bartels, , , Geomagnetism, , 2 vols., xxviii + pp., Oxford University Press, , 1940, . (The lunar magnetic variations are discussed in chapters 5, 9, 19, 20, and 23.)
2. Physics of the Earth;Fleming,1939
3. Bartels, J., , and G., Fanselau, , , Geophysikalische Mondtafeln, 1850– 1975, . Geophys. Inst. Potsdam Abh. No. 2, 44 pp., J. Springer, Berlin, 1938. (These tables supplement the same authors' “Geophysical lunar almanac,” Zs. Geophysik, v. 13, pp. 311–328, 1937; partly translated in Terr. Mag., v. 43, pp. 155–158, 1938.)