V. D. Zheljazkov and Nielsen, N. E.,
“Studies on the Effect of Heavy Metals (Cd, Pb, Cu, Mn, Zn and Fe) upon the Growth, Productivity and Quality of Lavender (Lavandula angustifolia Mill.) Production”,
Journal of Essential Oil Research, vol. 8, no. 3, pp. 259 - 274, 1996.