Suggestions for hummingbird books (1 Viewer)

I am looking for suggestions on books about hummingbirds. Anyone come accross one or two that are a little more scientific than those that are about attracting and a general overview of the hummingbirds that visit North America backyards?

Some will disagree but I like Sheri L. Williamson's Hummingbirds of North America - it is a Peterson Field Guide. Sheri is a contributor on the Hummingbird forum. Good plates with pictures of not just the bird as a whole but also the heads and tail-feathers (as separate plates). The species accounts include: a short general description, a more detailed description of the male, female and juvenile, similar species, sounds, behavior, habitat, status and conservation, and subspecies and taxonomic relations.

I have read Sheri's books and learned a lot from them. I also enjoy her contribution to the hummingbird forum here. She is a wealth of knowledge on the topic.