Mikhail B. Sevryuk Articles for an Encyclopaedia on Mathematical Physics (403K, pdf) ABSTRACT. This is a collection of 9 articles (on KAM theory and related topics) I was asked to write for an encyclopaedia on mathematical physics at the end of 2006. By April 19, 2007, the articles were prepared, but publication of the encyclopaedia is put off till the indefinite future. So I have decided to archive the articles lest they be lost. No changes or updates of the articles have been made.