2003, Gabrielle Walker, Snowball Earth: The Story of a Maverick Scientist and His Theory of the Global Catastrophe That Spawned Life As We Know It, Three Rivers Press, pages 34–35
2008, Barbara L. Bellman, Susan Goldstein, Flirting After Fifty: Lessons for Grown-Up Women on How to Find Love Again, iUniverse, published 2008, page 12