I just received my copy of Mac OS X and iOS Internals, and there is something a little strange:
Chapter 13: BS"D: The BSD Layer
Is there an explanation for the extra quote ?
it's not a typo. And it's not an allusion to Jewish roots, though the origin is Jewish. BS"D is yiddish for with the help of a greater power (as in, God). The idea in this chapter is that OS X goes to where it did with the help of a greater foundation, BSD's. It also ties in to "On the Shoulders of Giants", which is Chapter 3, which is the user-mode mirror image of that chapter.
All the chapters have double titles. Makes for a more interesting read :-)
BSD is an acronym for Berkeley Software Distribution and shouldn't carry the ". Probably a typo.