Nageswara Rao, R., P. Nagaraju, C. Srinivasulu, P. Radha Krishnamurthy, D. Sireesha, and V. Sumanth Reddy. 2016. “Spectrophotometric Determination of Butorphanol Tartrate and Telmisartan in Bulk and Pharmaceutical Formulations”. Asian Journal of Chemistry 16 (3):1953-55. https://asianpubs.org/index.php/ajchem/article/view/14448.