From the reviews: "[This] book presents the essential features of the theory on SLn(R). This makes the book accessible to a wide class of readers, including nonexperts of Lie groups and representation theory and outsiders who would like to see connections of some aspects with other parts of mathematics. This feature is widely to be appreciated, together with the clearness of exposition and the way the book is structured." -Sergio Console, Zentralblatt "This book is devoted to Harish-Chandra's Plancherel inversion formula in the special case of the group SLn(R) and for spherical functions. ... the book is easily accessible and essentially self contained." (A. Cap, Monatshefte fur Mathematik, Vol. 140 (2), 2003) "Roughly, this book offers a 'functorial exposition' of the theory of spherical functions developed in the late 1950s by Harish-Chandra, who never used the word 'functor'. More seriously, the authors make a considerable effort to communicate the theory to 'an outsider'. ... However, even an expert will notice several new and pleasing results like the smooth version of the Chevally restriction theorem in Chapter 1." (Tomasz Przebinda, Mathematical Reviews, Issue 2002 j) "This excellent book is an original presentation of Harish-Chandra's general results ... . Unlike previous expositions which dealt with general Lie groups, the present book presents the essential features of the theory on SLn(R). This makes the book accessible to a wide class of readers, including nonexperts ... . This feature is widely to be appreciated, together with the clearness of exposition and the way the book is structured. Very nice is, for instance, the ... table of the decompositions of Lie groups." (Sergio Console, Zentralblatt MATH, Vol. 973, 2001)