Zachariah JT, Gopalam A
Indian Perfumer, 1987
Essential oils are defined as the volatile oils obtained by steam or hydro distillation containing variety of organic compounds generally belonging to class of acyclic, isocyclic hydrocarbons, tri-and sesquiterpenoids and their oxygenated derivatives.
Zachariah JT, Gopalam A. Nature, Production and Quality of Essential Oils of Pepper, Ginger, Turmeric, Cardamom and Tree Spices. Indian perfum. 1987;31(3):188-205.