Queen's Gambit Declined: Orthodox Defense books?

What books do you guys recommend that talk about the Queen's Gambit Declined: Orthodox Defense?

I already have Sadler's Queen's Gambit Declined book.  

i also have the same book.I could say that sadlers book gives the basic themes of the opening.The rest is up to you to familiarize yourself as to how the opening would reach certain positions.

Does the book "Declining the Queen's Gambit" by John Cox talk about the Orthodox Defense?

The book covers the Tartakower Variation and the Lasker Defense, but it doesn't do much "talking."  The book just gives current theory without much explanation.  I would recommend the Starting Out series  if you are looking for explanations of moves.

Is Sadler's not enough? I thought he explained everything really well and I never really felt a need to read more than his book. Of course some specific lines are missing IIRC, perhaps you're looking to play one of them?