1. Futterman, S. Enzymatic reduction of folic acid and dihydrofolic acid to tetrahydrofolic acid. J. Biol. Chem. 228, 1031–1038 (1957).
2. Osborn, M. J. & Huennekens, F. M. Enzymatic reduction of dihydrofolic acid. J. Biol. Chem. 233, 969–974 (1958).
3. Burchall, J. J. & Hitchings, G. H. Inhibitor binding analysis of dihydrofolate reductases from various species. Mol. Pharmacol. 1, 126–136 (1965).
4. Peters, J. M. & Greenberg, D. M. Dihydrofolic acid reductase. Nature 181, 1669–1670 (1958).
5. Schweitzer, B. I., Dicker, A. P. & Bertino, J. R. Dihydrofolate reductase as a therapeutic target. FASEB J. 4, 2441–2452 (1990).