1. Integral Equations;WIARDA,1933
2. É. GOURSAT; Course of Mathematical Analysis Vol. III, ch. II. Gostekhizdat 1934. Translated from French. (Cours d'Analyse Mathématiqus Tome III, Pt. II. Gauthier-Villars, Paris, 1923.).
3. N. M. GÜNTHER; Foundations of Mathematical Physics Ch. I: Integral equations. Izd. Kubuch. L-d, 1931.
4. R. COURANT and D. HILBERT; Methods of Mathematical Physics Pt. I Gostekhizdat, 1933; especially ch. III. Translated from German. (Interscience Publishers, New York & London, 1953.).
5. W. V. LOVITT; Integral Equations. Gostekhizdat, 1933. Translated from English. (McGraw-Hill Book Co., Inc., New York & London, 1924.).