Rujukan Kelimpahan semula jadi

  1. ↑ Uranium Isotopes, dicapai 14 Mac 2012 
  2. ↑ Robert N. Clayton (1978) Isotopic anomalies in the early solar system, Annual Review of Nuclear and Particle Science 28:501-522.
  3. ↑ Ernst Zinner (2003) An isotopic view of the early solar system, Science 300:5617, 265-267.
  4. ↑ Ernst Zinner (1998) Stellar nucleosynthesis and the isotopic composition of presolar grains from primitive meteorites, Annual Review of Earth and Planetary Sciences 26:147-188.