Comparison of free tryptophan, bound tryptophan and tyrosine in plasma, and tryptophan, 5-hydroxytryptophan, serotonin, 5-hydroxyindoleacetic acid, tyrosine, dopamine and norepinephrine in brain parts of rat and pigeon.
Lane JD, Smith JE, Aprison MH. Comp Biochem Physiol B. 1976; 53(4):469-72.