TY JOUR TI Determining the size and viability of pollen of local and introduced species of birch trees KW pollen KW viability KW size KW male gametophyte KW polymorphism JO Forestry Engineering Journal AU Isakov, I.. AU Mantseva, M.. PY 2015 IS 5 PB FSBE Institution of Higher Education Voronezh State University of Forestry and Technologies named after G.F. Morozov