K.  Kautharapu, Pujari, N. S., Golegaonkar, S. B., Ponrathnam, S., Nene, S. N., and Bhatnagar, D., ?Vinyl-2-pyrrolidone derivatized guar gum based aqueous two-phase system?, Separation and Purification Technology, vol. 65, no. 1, pp. 9-13, 2009.