PAVLOV, Ivan Petrovich. Dvadtsatiletnii opyt ob"ektivnogo izucheniia vysshei nervnoi deiatel'nosti [Twenty years' Experience in the objective Study of the higher Nervous Behaviour of Animals. Conditioned Reflexes. A collection of articles, reports, lectures and speeches,] Moscow and Petrograd: State Publishers, 1923, 8°, FIRST EDITION, illustrations (a few leaves slightly stained), contemporary cloth-backed boards (rubbed); Lektsii o rabote glavnykh pishchevaritel'nykh zhelez [Lectures on the Function of the main Digestive Glands. New edition revised by the author,] Moscow: Priroda, 1917, 8°, portrait, original cloth (scuffed). (2)