S. A.  Agarkar, Kulkarni, R. R., Dhas, V. V., Chinchansure, A. A., Hazra, P., Joshi, S. P., and Ogale, S. B., ?Isobutrin from butea monosperma (flame of the forest): a promising new natural sensitizer belonging to chalcone class?, ACS Applied Materials & Interfaces, vol. 3, no. 7, pp. 2440-2444, 2011.