参考文献:
Doores, Katie J. Fulton, Zara Hong, Vu Patel, Mitul K. Scanlan, Christopher N. Wormald, Mark R. Finn Burton, Dennis R. Wilson, Ian A. Davis, Benjamin G. Proceedings of the National Academy of Sciences of the United States of America, 200 , vol. 07, # 40 p. 707 - 72