The Best Introductory Book on Ordinary Differential Equations
I highly recommend Ordinary Differential Equations, a classic mathematics book published by Dover that provides a comprehensive overview of equations describing relationships between variables and their derivatives—commonly known as ordinary differential equations (ODEs). The authors, Morris Tenenbaum (Professor of Mathematics at Cornell University) and Harry Pollard (Professor of Mathematics at Purdue University), present complex and crucial concepts in ODEs in a clear, step-by-step manner, making the material accessible to undergraduate students in mathematics, engineering, and science without sacrificing mathematical rigor.

The book begins by exploring the origins of differential equations, defining fundamental terminology, and outlining the general solution of differential equations—namely, solutions that encompass all possible cases. Subsequent chapters cover topics such as integrating factors, dilution and proliferation problems, complex algebra; linearization of first-order systems, Laplace transforms, Newton’s interpolation formula, and Picard’s successive approximations.
Two particularly outstanding sections stand out: one focuses on series methods for solving differential equations, and the other discusses numerical methods for their solution. Chapter One addresses Legendre differential equations, Legendre functions, Legendre polynomials, Bessel differential equations, and Laguerre differential equations. Throughout the book, all terms are clearly defined, and each theorem is examined thoroughly and insightfully, achieving a remarkable balance between the theory and applications of differential equations. A wealth of exercises and problems enhances the book’s value as a textbook for both undergraduates and instructors. The final chapters delve deeply into existence and uniqueness theorems for various differential equations and introduce determinant theory and the Wronskian theorem.
Originally published in the mid-20th century, this is a highly regarded introductory textbook on ODEs, known for being exceptionally self-study friendly. It has received widespread acclaim since its release, influencing multiple generations. Many readers have learned to solve ODEs from the ground up thanks to this book.