Nikolova-Alexieva, Valentina, and Katina Valeva. “INFLUENCE OF COVID-19 ON THE INNOVATION ACTIVITY OF THE BIO-SECTOR IN BULGARIA”. KNOWLEDGE - International Journal , vol. 49, no. 1, Dec. 2021, pp. 89-95, https://ikm.mk/ojs/index.php/kij/article/view/4623.