Asekun, O.T.; Grierson, D; Afolayan, A; et al. Effects of drying methods on the quality and quantity of the essential oil of Mentha longifolia L. subsp. Capensis. Food Chemistry. 2006, 101 (3): 995–998. doi:10.1016/j.foodchem.2006.02.052.
Farley, Derek R.; Valerie Howland. The natural variation of the pulegone content in various oils of peppermint. Journal of the Science of Food and Agriculture. 2006, 31 (11): 1143–1151. doi:10.1002/jsfa.2740311104.