http://fsweb2.schaub.ncsu.edu/usdaars/acrobatpubs/s114-150/s132.pdf Van-Den Truong, Nigel Deighton, Roger T. Thompson,
Roger F. McFeeters, Lisa O. Dean, Kenneth V. Pecota, and
G. Craig Yencho "Characterization of Anthocyanins and Anthocyanidins in
Purple-Fleshed Sweetpotatoes by HPLC-DAD/ESI-MS/MS" Journal of Agricultural and Food Chemistry, 2009
