Prepn: Janssen, US 2979508 (1961). Synthesis of labeled compound: Soudijn, van Wijngaarden, J. Lab. Comp. 4, 159 (1968). Distribution and metabolism studies in rat and pig: Heykants et al., Arzneim.-Forsch. 21, 982, 1263, 1357 (1971). Veterinary clinical studies: Symoens, van den Brande, Vet. Rec. 85, 64 (1969). Crystal structure: M. H. J. Koch et al., Acta Crystallogr. 33B, 1975 (1977).