apollo. (2026). VLF survey of Hessdalen valley, about 100 km of traces at 20 m spacing (Vargemezis et al. 2024) (Version 1.0) [Data set]. Mysteries Department. https://mysteriesdept.com/datasets/DAT0D0NE3BG2A6K/vlf-survey-of-hessdalen-valley-about-100-km-of-traces-at-20