Composition #2: Li, XN., Ma, RY., Su, HH., Sun, HH., Ma, GH., Su, ZG., Zha, SH. Rapid purification of huperzine A and B with two polystyrene based resins by preparative low-pressure liquid chromatography . journal of liquid chromatography & related technologies, 2006, vol. 29, no. 4, p. 569–582. DOI: 10.1080/10826070500479302.
[
DOI link]