H.-W. Gao, J.-S. Gu, S.-R. Shi, and H. Ye, “Updated Spectrophotometric Investigation of Neodymium Complexes formed with 1-(2-Pyridylazo-2-Naphthal and 2-(5-Bromo-2-Pyridylazo)-5-Diethylamino-m-Phenol ”, ajc, vol. 14, no. 1, pp. 349–356, Mar. 2010.