G. Angelova, Svetla, et al. “A Review on Antitumor and Antiviral Potential of Cranberries (Vaccinium Vitis-Idaea) Origin from Bulgaria”. American Scientific Research Journal for Engineering, Technology, and Sciences, vol. 49, no. 1, Nov. 2018, pp. 1-7, https://www.asrjetsjournal.org/American_Scientific_Journal/article/view/4472.