Handbook of Differential Equations, 4th Edition

The book is a compilation of methods for solving and approximating differential equations. These include the most widely applicable methods for solving and approximating differential equations,　as well as　numerous methods. Topics include methods for ordinary differential equations, partial differential equations, stochastic differential equations, and systems of such equations.
Included for nearly every method are:
The types of equations to which the method is applicable
The idea behind the method
The procedure for carrying out the method
At least one simple example of the method
Any cautions that should be exercised
Notes for more advanced users
The fourth edition includes corrections, many supplied by readers, as well as many new methods and techniques. These new and corrected entries make necessary improvements in this edition.