Konieczyński, Paweł, and Marek Wesołowski. “Analysis of Nitrate Nitrogen in Leaves and Roots With Rhizomes of Medicinal Plants”. Current Issues in Pharmacy and Medical Sciences, vol. 24, no. 2, Jan. 2012, pp. 105-11, https://czasopisma.umlub.pl/curipms/article/view/3011.