Dinev, Nikolai, Vesselin Kutev, Mariana Hristova, Ivanka Mitova, and Ana Katzarova. 2021. “Effect of Various Enhancers on the Bioavailability of Heavy Metals and Their Accumulation in Lettuce (Lactuca Sativa L.)”. Bulgarian Journal of Soil Science, Agrochemistry and Ecology 55 (2): 65-75. https://agriacad.eu/ojs/index.php/bjssae/article/view/1625.