J.-X. Yang, H.-W. Gao, S.-R. Shi, H.-Z. Dong, T.-J. Wang, and Q.-L. Liu, “Determination of Characteristic Constants of Nickel and Manganese Complexes with p-Nitro-o-carboxylazo-chromotropic Acid ”, ajc, vol. 13, no. 2, pp. 631–638, Mar. 2010.