1. Ender J (2002) 98 years of the RADAR principle: the inventor Christian Hülsmeyer. EUSAR
2. Kozlovsky EA (1989) Encyclopaedia of mining (in Russian), vol 4. Ed. Sovietic Encyclopaedia, pp 285–286
3. Finkelshtein MI, Kutev VA, Zolotared VP (1986) Applications of ground penetrating radar in geological engineering (in Russian). Ed. Nedra, Moscow
4. http://www.radarworld.org/huelsmeyer.html. Access 11 May 2020
5. http://www.ieeeghn.org/wiki/index.php/Radar_during_World_War_II#Radar_during_World_War_II. Access 11 May 2020