### Instruction:
Based on this paragraph, tell me who was responsible for the discovery of nuclear fission.

### Input:
Nuclear fission of heavy elements was discovered on Monday 19 December 1938 in Berlin, by German chemist Otto Hahn and his assistant Fritz Strassmann in cooperation with Austrian-Swedish physicist Lise Meitner. Hahn understood that a "burst" of the atomic nuclei had occurred. Meitner explained it theoretically in January 1939 along with her nephew Otto Robert Frisch. Frisch named the process by analogy with biological fission of living cells. In their second publication on nuclear fission in February of 1939, Hahn and Strassmann predicted the existence and liberation of additional neutrons during the fission process, opening up the possibility of a nuclear chain reaction.

### Response:
Otto Hahn and his assistant Fritz Strassmann achieved nuclear fission in the laboratory, but could not explain what had happened. It was Lise Meitner and her nephew Otto Robert Frisch that interpreted the laboratory results and discovered that nuclear fission had occurred.