ArticleIssue Date2008CitationPROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, v.105, no. 7, pp 2397 - 2402PublisherNATL ACAD SCIENCES
ArticleIssue Date2012CitationPROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, v.109, no.20, pp 7636 - 7641PublisherNATL ACAD SCIENCES