macOS Book Suggestions - PHP5 and C

[hiddenpremise]

I am looking for two solid book suggestions. I know both languages, but would like a good reference.

The book on C should be from a UNIX administrator's point of view.

Please share any experiences you have had with books on these topics.
I am not looking for C++, Ojb-C, C#, etc. Just plain old C for Unix.

Thanks much