Since QCD is an ever growing area of physics, a number of sections in this third
edition of the book have been expanded, in particular, those dealing with deep
inelastic scattering. Here new material is included both on higher-order
calculations, quite a number of which have become available in the last few
years, and on the small-x limit of structure functions, where, triggered by the
results of HERA, there has been considerable activity. Two other topics have
also received special attention. One is the matter of bound states of heavy
quarks, where inclusion of higher-order perturbative and nonperturbative
corrections has led to a clarification of the QCD