This is volume 11 of HBW or "Handbook of the Birds of the World", a 16-volume encyclopedia and scientific reference work covering all (!) species of birds. The entire series took 19 years to publish, so the editors at Lynx Edicions must have been very satisfied indeed when the last volume hit the stores late last year.
The eleventh volume was published in 2006. It covers a number of passerine families, most notably the Old World Warblers. Indeed, about half of this grand volume deals with the warblers. The rest of the book covers Old World Fly-catchers, Batises and Wattle-Eyes, Kinglets and Firecrests, Fantails, Cisticolas and allies, Monarch Fly-catchers, and Gnatcatchers. I readily admit that I never heard of many of these families before. Gnatcatchers? As opposed to Fly-catchers, presumably...
As usual, each family is introduced with an extensive chapter on systematics, morphology, habitat, habits, relationship with man and conservation status. Species presentations follow. All species are illustrated on the color plates. In addition, the book also contains real color photographs of many of the birds mentioned in the text. It's the photos that mark HBW out from normal reference works of this kind, which are all text and very little pictures. I think the photos are the main reason why Lynx Edicions are promoting the HBW on the commercial market, despite the heavy, non-popularized character of the text.
Obviously, HBW volume 11 is worth five stars.