Hildebrand P., Königschulte W., Gaber T. J., Bubenzer-Busch S., Helmbold K., Biskup C. S., Langen K.-J., Fink G. R. and Zepf F. D. (2015) “Effects of dietary tryptophan and phenylalaninetyrosine depletion on phasic alertness in healthy adults - A pilot study”, Food & Nutrition Research, 59. doi: 10.3402/fnr.v59.26407.