Inge Lehmann (May 13, 1888 – February 21, 1993) was a Danish seismologist and geophysicist. In 1936, she discovered that the Earth has a solid inner core inside a molten outer core. Before that, scientists believed Earth's core to be a single molten sphere. However, seismologists had been unable to explain careful measurements of seismic waves from earthquakes, which were inconsistent with the Earth having a single molten core. Lehmann analysed the seismic wave measurements, and she concluded that Earth must have a solid inner inside a molten outer core to produce seismic waves that matched the measurements. Other seismologists tested and then accepted Lehmann's explanation. 
- "Lehmann, Inge". Complete Dictionary of Scientific Biography. Detroit, MI: Charles Scribner's Sons. 2008. http://www.encyclopedia.com/topic/Inge_Lehmann.aspx. Retrieved 15 October 2013.
- "Lehmann; Inge (1888–1993)". The Royal Society: Past Fellows. https://collections.royalsociety.org/DServe.exe?dsqIni=Dserve.ini&dsqApp=Archive&dsqDb=Persons&dsqSearch=Code==%27NA5258%27&dsqCmd=Show.tcl. Retrieved 24 September 2013.
- Bolt, Bruce A. (January 1994). "Inge Lehmann". Physics Today 47 (1): 61. doi:10.1063/1.2808386.