Broek, T. A. B., & McCarthy, M. D. (2014). A new approach to δ15N compound-specific amino acid trophic position measurements: preparative high pressure liquid chromatography technique for purifying underivatized amino acids for stable isotope analysis. Limnology and Oceanography: Methods, 12(12), 840–852. doi:10.4319/lom.2014.12.840