U. Jordis: "Synthesis of dithiooxolinic acid"; Monatshefte für Chemie, 117 (1986), 11; S. 1339 - 1342.
5-Aminobenzene-1,3-dithiol, available by redn. of 5-aminobenzo-1,3-dithiol-2-thione I was elaborated into dithiooxolinic acid II.