1. The Essential Oils, Vol. V, p. 440, Van Nostrand, New York (1952).
2. Coltivazioni delle Piante Officinali, p. 143, Clesav, Milan (1985).
3. Flora d'Italia, Edagricole, Bologna (1982).
4. Essential Oils 1979–1980, p. 17, Allured Publishing, Wheaton, IL (1981).