**All of the books listed below may be downloaded gratis from
the links provided.** Some of these books are also offered for sale
online by third parties. Though reselling is technically legal (if the
books are in the public domain), the practice amounts to capitalizing
on readers' ignorance that the book is available at no cost. Further,
reselling misappropriates the credit due to the digitizer, or worse,
damages high-quality typographical work but sells it with the
digitizer's name still attached. Please read the short essay,

**Categories:**

- Mathematics.
- History, Philosophy, Recreation, General Interest.
- School Algebra, Abstract Algebra, Combinatorics.
- Calculus, Analysis, Differential Equations, Geometry.
- Logic, Philosophy, Probability.
- Physics

- Astronomy.

- Florian Cajori:

*A History of Mathematics*. - Augustus De Morgan:

*On the study and difficulties of mathematics*. - Felix Klein:

*The Evanston Colloquium (1893)*. - Henri Poincaré:

*Science and Hypothesis*. - William Frank White:

*A Scrap-Book of Elementary Mathematics*.

- William Burnside:

*Theory of Groups of Finite Order*. - Leonard Eugene Dickson:

*First Course in the Theory of Equations*. - Évariste Galois:

*Oeuvres mathématiques d'Évariste Galois*. - Joseph Louis Lagrange:

*Lectures on Elementary Mathematics*. - John W. Moon:

*Topics on Tournaments*. - George Albert Wentworth:

*The First Steps in Algebra*.

- Karl Friedrich Gauss:

*General Investigations of Curved Surfaces of 1827 and 1825*. - Jacques Hadamard:

*Four Lectures on Mathematics*. - Godfrey Harold Hardy:

*Orders of Infinity: The `Infinitärcalcül' of Paul Du Bois-Reymond*. - Godfrey Harold Hardy:

*A Course of Pure Mathematics*. - Felix Klein:

*On Riemann's Theory of Algebraic Functions and their Integrals*. - Augustus De Morgan:

*Elementary Illustrations of the Differential and Integral Calculus*. - Sylvanus Phillips Thompson:

*Calculus Made Easy*.

- George Boole:

*The Mathematical Analysis of Logic*. - John Maynard Keynes:

*A Treatise on Probability*. - Bertrand Russell:

*Introduction to Mathematical Philosophy*. - Alfred North Whitehead:

*An Introduction to Mathematics*.

- Arthur Stanley Eddington:

*Space, Time and Gravitation*. - Albert Einstein:

*Relativity: The Special and the General Theory, 3*.^{rd}Ed - Albert Einstein:

*The Meaning of Relativity: Four Lectures Delivered at Princeton, May, 1921*. - Max Planck:

*The Theory of Heat Radiation*. - Hermann Weyl:

*Space--Time--Matter*.

- Forest Ray Moulton:

*An Introduction to Astronomy*. - George Howard Darwin:

*The Tides and Kindred Phenomena in the Solar System*.