There seems to be two types of books on inequalities. On the one hand
there are treatises that attempt to cover all or most aspects of the
subject, and where an attempt is made to give all results in their best
possible form, together with either a full proof or a sketch of the
proof together with references to where a full proof can be found. Such
books, aimed at the professional pure and applied mathematician, are
rare. The first such, that brought some order to this untidy field, is
the classical "Inequalities" of Hardy, Littlewood & P6lya, published in
1934. Important as this outstanding work was and still is, it made no
attempt at completeness; rather it consisted of the total knowledge of
three front rank mathematicians in a field in which each had made
fundamental contributions. Extensive as this combined knowledge was
there were inevitably certain lacunre; some important results, such as
Steffensen's inequality, were not mentioned at all; the works of certain
schools of mathematicians were omitted, and many important ideas were
not developed, appearing as exercises at the ends of chapters. The later
book "Inequalities" by Beckenbach & Bellman, published in 1961, repairs
many of these omissions. However this last book is far from a complete
coverage of the field, either in depth or scope.