First survey of the vascular and cryptogam flora on Bulgaria's ancient mounds.

Apostolova, I., Sopotlieva, D., Valcheva, M., Ganeva, A., Shivarov, V., Velev, N., Vassilev, K., Terziyska, T., Nekhrizov, G., (2022). Plants 11(5) MDPI AG, Basel, Switzerland. English language

Ecosystem condition assessment of semi-natural grasslands outside the Natura 2000 network in Bulgaria, using vegetation data.

Sopotlieva, D., Velev, N., Tsvetkova, N., Vassilev, V., Apostolova, I., (2018). Tuexenia(No.38), 385-404. Floristisch-Soziologische Arbeitsgemeinschaft e.V., Göttingen, Germany. English language

The contradiction between taxa of conservation significance and invasive species - a case study of sustainable development in Mala Planina.

Grigorov, B., Vassilev, K., Velev, N., Assenov, A., (2016). European Journal of Sustainable Development 5(4), 464-474. European Center of Sustainable Development, Rome, Italy. English language