Stark Pharm's Flex GCM formula...
Dietary supplement OstroVit - Tryptophan is a precursor of serotonin, it is also an intermediate for the production of melatonin.
BioTech Dietary Supplement - L-Tryptophan - tryptophan is an essential amino acid that performs numerous functions in the body, including as a precursor of serotonin and melatonin.