Chicken incubation and hatching books

The internet is chock full of information about hatching chicken eggs...but it's all the same information repeated over and over on different websites.  Yes, the basic humidity, days to hatch, and temperature information is important, but what if you want to delve deeper into learning about incubation?  Am I really the only nervous chicken mother who wants to know what percentage of chicks get out of the shell on day 21 during an optimal hatch and when it's kosher to help chicks?  That's when you give up on websites and move to books.

Most of the modern books I've browsed present the same information that can be found on the web, with my favorite so far being the "hatchery and incubation" chapter in Day Range Poultry by Andy Lee and Patricia Foreman.  You can tell that the duo have had quite a bit of hands-on experience, and they present more than the basics, although still only enough to whet my appetite.  Storey's Guide to Raising Chickens by Gail Damerow also has a long chapter on incubation, but the text seems to be heavy on operation of the actual incubator and on chick identification methods and light on the biological information I crave.  Despite the name, Success With Baby Chicks by Robert Plamondon  starts when the box of chicks arrives from the hatchery and doesn't consider incubation at all.  Finally, The Incubation Book by A.F. Anderson-Brown looks interesting, but I haven't been able to get my hands on a copy yet.

Eventually, it occurred to me that chickens have been hatching for a very long time, and I should take a look at old books in the public domain.  Two of the ones I rustled up were worthless, but I stumbled across a real gem in the 105 year old Incubation: Natural and Artificial, by J.H. Sutcliffe.  This out of print book is available as a free ebook, and you can download the pdf version by clicking on this link.  (Alternatively, visit OpenLibrary to see other file formats.)  So far, I've only dipped into the hatching chapter (which already answered half of my most pressing questions), but I plan to read the book more carefully later, especially the introduction that discusses how Egyptians have artificially incubated eggs for thousands of years.

I'm still looking for answers, though, and could use some more book recommendations.  Which books have you found eased your mind during incubation?