Knapp, A.N., D.M. Sigman, and F. Lipschultz. 2005. “N Isotopic Composition of Dissolved Organic Nitrogen and Nitrate at the Bermuda Atlantic Time-Series Study Site”. Global Biogeochemical Cycles 19: 1-15. doi:10.1029/2004GB002320.

Hastings, M.G., D.M. Sigman, and F. Lipschultz. 2003. “Isotopic Evidence for Source Changes of Nitrate in Rain at Bermuda”. Journal of Geophysical Research: Atmospheres 108. Blackwell Publishing Ltd: 22-1. doi:10.1029/2003jd003789.

Karl, D., A. Michaels, B. Bergman, D. Capone, E. Carpenter, R. Letelier, F. Lipschultz, H. Paerl, D. Sigman, and L. Stal. 2002. “Dinitrogen Fixation in the World S Oceans”. Biogeochemistry 57-58: 47-98. doi:10.1023/A:1015798105851.

Knapp, A.N., D.M. Sigman, F. Lipschultz, A.B. Kustka, and D.G. Capone. 2011. “Interbasin Isotopic Correspondence Between Upper-Ocean Bulk DON and Subsurface Nitrate and Its Implications for Marine Nitrogen Cycling”. Global Biogeochemical Cycles 25. doi:10.1029/2010GB003878.

Knapp, A.N., M.G. Hastings, D.M. Sigman, F. Lipschultz, and J.N. Galloway. 2010. “The Flux and Isotopic Composition of Reduced and Total Nitrogen in Bermuda Rain”. Marine Chemistry 120: 83-89. doi:10.1016/j.marchem.2008.08.007.

Knapp, A.N., P.J. Difiore, C. Deutsch, D.M. Sigman, and F. Lipschultz. 2008. “Nitrate Isotopic Composition Between Bermuda and Puerto Rico: Implications for N2 Fixation in the Atlantic Ocean”. Global Biogeochemical Cycles 22. doi:10.1029/2007GB003107.