books.google.com - 'This is an excellent book from which to learn the methods and results of statistical mechanics.' Nature 'A well written graduate-level text for scientists and engineers... Highly recommended for graduate-level libraries.' Choice This highly successful text, which first appeared in the year 1972 and...http://books.google.com/books/about/Statistical_Mechanics.html?id=PIk9sF9j2oUC&q=approximation&utm_source=gb-gplus-shareStatistical Mechanics