Jordan, Vanderbilt University Press, 2006, pp. 2–4. ISBN 0-8265-1528-2, ISBN 978-0-8265-1528-5. Kunstler, James Howard. The Long Emergency. Grove Press. 2005:
Anita H. Payne; Matthew P. Hardy. The Leydig Cell in Health and Disease. Springer Science & Business Media. 28 October 2007: 186–. ISBN 978-1-59745-453-7
Key Stages in the Formation of Central European Mitochondrial Genetic Diversity. Science (American Association for the Advancement of Science). December