(Netherlands: Springer, 2006.) "Uranium". Encyclopaedia Britannica. Retrieved 22 April 2017. "Uranium". Royal Society of Chemistry. "Uranium". The McGraw-Hill Science
isotope of the element. However, three elements, Thorium, Protactinium, and Uranium, have a characteristic terrestrial isotopic composition, and thus their
Digital Library for Nuclear Issues Archived 2006-08-28 ವೇಬ್ಯಾಕ್ ಮೆಷಿನ್ ನಲ್ಲಿ. "Cleavage of the Uranium Nucleus", Physical Review, Received 3 February 1939