R. Courant, H. Robbins, I. Stewart, What is Mathematics?, Oxford Press. (Recommended by Boaz Klartag, Weizmann Institute).

From the series Popular Lectures in Mathematics, translated and adapted from the Russian, and published by the University of Chicago Press (Recommended by David Gilat, Tel Aviv University):

• Criteria for Divisibility, by N. N. Vorob'ev

• Systems of Linear Equations, by A. S. Solodovnikov

• Inversions, by I. Ya. Bakel'man

• The Decomposition of Figures Into Smaller Part, by V. G. Boltyanskii and T. I. Gohberg

William Dunham, Journey Through Genius - The Great Theorems of Mathematics, Penguin Books, 1991 (Recommended by David Gilat, Tel Aviv University).

William Dunham, EULER The Master of Us All, Math. Assos. Am. (MAA), 1999 (Recommended by David Gilat, Tel Aviv University).

Hans Rademacher and Otto Toeplitz, The Enjoyment of Mathematics, Princeton U. Press, 1966 (7th printing) (Recommended by David Gilat, Tel Aviv University).

The books by I.M. Gelfand (on Algebra, Trigonometry, The Method of Coordinates, Functions and Graphs). See for example this book. (Recommended by Uri Bader, Weizmann Institute).

V. B. Alekseev, after V.I. Arnold, Abel's Theorem in Problems and Solutions. (Recommended by Inna Entova, Ben Gurion University).