A Modified Two-queen System: “Tower” Colonies Allowing For Easy Drone Brood Removal for Varroa Mite Control, Science of Bee Culture, Dennis vanEngelsdorp, Shane Gebauer, and Robyn Underwood http://maarec.psu.edu/CCDPpt/TwoQueenSystemFeb2009.pdf
A Survey of Honey Bee Colony Losses in the U.S., Fall 2007 to Spring 2008, PLoS ONE, Dennis vanEngelsdorp, Jerry Hayes, Jr., Robyn M. Underwood and Jeffrey Pettis http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0004071
Penn State Live Press Release “Bee Researchers Close in on Colony Collapse Disorder http://live.psu.edu/story/25747
American Bee Journal Article – “An Estimate of Managed Colony Losses in the Winter of 2006 – 2007: A Report Commissioned by the Apiary Inspectors of America by Dennis vanEngelsdorp, Robyn Underwood, Dewey Caron, Jerry Hayes, Jr. http://maarec.psu.edu/CCDPpt/CCDJuly07ABJArticle-1.pdf
Summary of Research on the Non-target Effects of Bt Corn Pollen on Honeybees http://maarec.psu.edu/CCDPpt/NontargeteffectsofBt.pdf