From inosinic acid: Levene, Jacobs, Ber. 41, 2703 (1908); 44, 746 (1911); Levene, Mori, J. Biol. Chem. 81, 215 (1929); Levene, Stiller, ibid. 104, 299 (1934); LePage, Umbreit, ibid. 148, 255 (1943); Marmur et al., Arch. Biochem. Biophys. 34, 209 (1951). Purification: Groth et al., J. Biol. Chem. 199, 389 (1952). Differentiation between ribose-5-phosphate and ribose-3-phosphate by means of the orcinol-pentose reaction: Albaum, Umbreit, ibid. 167, 369 (1947).