_____CHELSEA SCIENTIFIC BOOKS DIFFERENTIALGLEICHUN-GEN: LOESUNGSMETHODEN UND LOESUNGEN, By E. Kamke. 3rd Edition. 1944. 692 pages. 6x9. Originally published at $15.00. $7.00 Everything possible that can be of use when one has a given differential equation to solve, or when one wishes to investigate that solution thoroughly. PART A: General Methods of Solution and the Properties of the Solutions. PART B: Boundary and Characteristic Value Problems. PART C: Dictionary of some 1600 Equations in Lexicographical Order, with solution, techniques for solving, and references. ASYMPTOTISCHE GESETZE DER WAHRSCHEINLICHKEITS-RECHNUNG, By A. A. Khintchine. 1933. 82 pages. 5j^x8j4, Paper. Originally published at $3.85. ^ $2.00 From the series Ergebnisse der Mathematik. ENTWICKLUNG DER MATHEMATIK IM 19. JAHRHUNDERT, By F. Klein. 2 Vols. 616 pages. 5j^x8j4. Originally published at $14.40. The set $7.00 "the fruit of a rich life lived in the midst of scientific events, the expression of superior wisdom and of a deep historical sense, of a highly cultured personality and of a masterly power of organization." óR. C our ant and 0. Neugebauer. VORLESUNGEN UBER HOHERE GEO-METRIE, By Felix Klein. Third edition. 413 pages. 5j^x8. Originally published at $10.80. $4.95 In this third edition there has been added to the first two sections of Klein's classical work a third section written by Professors Blaschke, Radon, Artin and Schreier on recent developments. THEORIE DER ENDLICHEN UND UNENDLICHEN GRAPHEN, By D. Konig. 1936. 269 pages. 5j4x8j4. Originally published at $7.20. $3.95 "an important branch of topology... "elegant applications to matrix theory ... abstract set theory . . . linear forms . . . electricity . . basis problems . . . "numerous applications to Logic, Theory of Games, Group Theory . . . problems of graph theory have a special inherent attractiveness independent of their applications."óL. Kalmar. Ada Szeaed.