Best Opening Book Move Variation Chart

I was curious as to what the most user friendly reference guide to opening theory is. I am looking for a guide that has a system that, quickly allows you to study through an opening, no matter what variations you want to study. In other words I don't want to have to go to another chapter to see another variation. I am looking for something this is charted, so you can quickly find the line of any variation for the most openings possible. Does anyone have any good recommendations? I prefer a book form.

Sahovski (of Chess Informant fame) publishes the Encylopaedia of Chess Openings (ECO) in five volumes.  Nick De Firmian also wrote a book called Modern Chess Openings (MCO), now in its 15th edition.  Older books like Nunn's Chess Openings (NCO) are probably still useful as well.  These are mostly just pages and pages of tables assessing different lines.  MCO and NCO have short written intros to each opening.

As far as I am concerned , it is books!

This is all you'll need.

Nick De Firmian, Modern Chess Openings (MCO), now in its 15th edition.

Very easy to work with.