Ashoori, D., Noorhosseini, S. A., & Safarzadeh, M. N. "Effect of Plant Density and Planting Pattern on Yield and Yield Components of Iranian Ox-Tongue (Echium amoenum Fisch. & Mey.) in Guilan Province", Journal of Horticultural Science, 28, 2, 2014, 135-143. doi: 10.22067/jhorts4.v0i0.39339