 Under the pseudonyms Christof Friedrich and Mattern Friedrich, Zündel also wrote several publications promoting the idea that UFOs were craft developed by German scientists who had fled to New Swabia, Antarctica.These titles include "Secret Nazi Polar Expeditions" (1978) and "Hitler at the South Pole" (1979).He promoted the idea of Nazi secret bases in Antarctica, Nazi UFOs, secret polar bases and Hollow Earth theories.