[Thickness of the epidermis and concentration of urocanic acid on the posterolateral (more pigmented) and anteromedial (less pigmented) side of the arm].
Biochem J. 1981 Mar 15;194(3):829-38. doi: 10.1042/bj1940829.
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Isolation and characterization of 3-[(carboxymethyl)thio]-3-(1H-imidazol-4-yl)propanoic acid from human urine and preparation of its proposed precursor, S-[2-carboxy-1-(1H-imidazol-4-yl)ethyl]cysteine.