Dyulgerski, Yovko, and Margarita Docheva. 2016. “Hybrydological Analysis of Inheritance of the Chemical Composition in Burley Tobacco Crosses. II. Sugars and Proteins”. Bulgarian Journal of Crop Science 53 (4): 57-62. https://agriacad.eu/ojs/index.php/bjcs/article/view/3220.