Tourism as a prerequisite for changing the national identity Tourism in Varna Black sea area – current situation and prospects for development Protected areas in the Stara planina tourist region – current state and prospects for tourism development Green infrastructure - the smart interpreting of natural capital Learning for sustainability - competences and expectations Opuntia fragilis (Nutt.) Haw. (Cactaceae) in the Bulgarian floraPotential health benefits of the plant Levisticum officinale (lovage) in relation to its polyphenolic contentThermodynamic solid-liquid equilibrium model for mixed systems HF-NaF-H2O and HF-KF-H2O up to 2 m HF at T = 25oC Editorial Note: Rhodopes Mountains - a fairy tale in green – Part I (Eastern Rhodopes)