Reference books that compliment FCC's HTML/CSS courses

I’m sure this has been asked in the past, but the posts I found seem to be a bit old. I was wondering if anyone had any suggestions for reference books that compliment the lessons on FCC?

The way FCC is laid out, it’s a little clumsy to go back to past lessons to look up things I forget (which seems to be everything.) Plus, I just like books!

Thank you for your time!