From the reviews: "This book is intended to be an introduction to variational methods for ODEs and PDEs. ... Overall, this is a well-written book on the variational methods ... . The author clearly loves and knows the subject area and it is very good at providing an overview to the area ... . As such, a good guided reading course for graduate students could be made from this book, covering one chapter per session (or two)." (David A. W. Barton, Dynamical Systems Magazine, April, 2008) "This little book consists of a very clear introduction to variational methods and their applications to ODEs and PDEs. ... the bibliography contains basic items on the subject and also turns out to be very useful for further reading. In my opinion the book should be strongly recommended to anyone-graduate student or researcher-who is interested in variational methods and their applications to differential equations." (Salvatore A. Marano, Mathematical Reviews, Issue 2008 k) "The intention of the author is to provide a first introduction to variational methods in solving ODEs and PDEs for graduate students. The book is a concise collection of some fundamental aspects of this area ... . It presents a nice and direct approach to these central topics and is written with great care and clarity. It can be warmly recommended to anyone wishing to enter this active area of research." (M. Kunzinger, Monatshefte fur Mathematik, Vol. 156 (4), April, 2009)

• Critical Points Via Minimization.- The Deformation Theorem.- The Mountain-Pass Theorem.- The Saddle-Point Theorem.- Critical Points under Constraints.- A Duality Principle.- Critical Points under Symmetries.- Problems with an S1-Symmetry.- Problems with Lack of Compactness.- Lack of Compactness for Bounded ?.