K. AGARWAL, R., and GYANENDRA SINGH . “Studies on Oxovanadium (IV) Complexes With 4-[(N-Acetyl) Amino]-Antipyrine ‡”. Asian Journal of Chemistry, vol. 1, no. 4, June 2010, pp. 409-12, https://asianpubs.org/index.php/ajchem/article/view/25431.