^Richey, D.P. & Brown, G.M. (1969). „The biosynthesis of folic acid. IX. Purification and properties of the enzymes required for the formation of dihydropteroic acid”. J. Biol. Chem. 244: 1582—1592. PMID4304228.
^Shiota, T., Baugh, C.M., Jackson, R. and Dillard, R. (1969). „The enzymatic synthesis of hydroxymethyldihydropteridine pyrophosphate and dihydrofolate”. Biochemistry. 8: 5022—5028. PMID4312465.CS1 одржавање: Вишеструка имена: списак аутора (веза)