Synthesis, characterization and augmented anticancer potential of PEG-betulinic acid conjugate - Seneja, A; Sharma, L; Dubey, R D; Mintoo, M J; Singh, A; Kumar, A; Sangwan, P L; Tasaduq, S A; Singh, G; Mondhe, D M; Gupta, P N (Mat Sci Eng C, 2017)