1. C. A. Heiland: Geophysical mapping from the air: its possibilities and advantages. Eng. and Min. J. 136, 609–610 (1935).
2. M. Grotewahl: Bericht über die Versuchsfahrt des Bidlingsmaierschen Doppelkompasses mit dem Luftschiff Graf Zeppelin. Terr. Magn. 35, 226–229 (1930).
3. H. Lundberg, and K. Sundberg: Discussion of paper by A. S. Eve, A.magnetic method of estimating the height of some buried magnetic bodies. Am. Inst. Min. Met. Eng. Geophysical Prospecting 209 (1932).
4. A. A. Logachev: The development and applications of airborne magnetometers in the U.S.S.R. Geophysics 11, No. 2, 135–147 (1946).
5. A. A. Logachev: The development and applications of airborne magnetometers in the U.S.S.R. Petrol. Eng. 17, No. 10, 211–218 (1946).