Possibly helpful:
Starting Out: Queen's Gambit Accepted by Alexander Raetsky & Maxim Chetverik (2006)
Starting Out: Queen's Gambit Declined by Neil McDonald (2006)
https://web.archive.org/web/20140627005627/http://www.chesscafe.com/text/hansen93.pdf
Starting Out: Slav and Semi-Slav by Glenn Flear
I'd recommend learning the Slav Defense (1. d4 d5 2. c4 c6). I've tried almost any d4 defense you could think of, and I think I'm going to stick with Slav for life (unless I get bored with it). It's really solid and you get a great game with it.
Quite like the a6 version of the slav, 1.d4 d5 2c4 c6 3Nc3 Nf6 4Nc3 a6. One of the main ideas is to develop normally with bf5/bg4 without giving up the centre with d5xc4. This is because can answer Qb3 with ra7 or b5. Probably least work of any defend, only need know a small set of concrete lines.
Yes the a6 lines are interesting, but I like white's position after c5. 4. e6 is the best in my opinion. Both are perfectly playable though.
As the second post indicates there is some heavy duty theory after 4...e6. If don't get involved in this, your playing a Queens Gambit were have played c6 unnecessarily early. Think inexperienced players would do better trying to solve problem of white squared bishop and avoiding e6.
4...a6 5c5 is one of cases were black should know something concrete with 5...nb-d7 preparing e5 for example. Think white would need to be quite a strong player to play the resulting positions well though.
I usually play the Queens Gambit Refused: Marshall Defense (1. d4 d5 2. c4 Nc6), but the Slav is also very good. I personally don't like 2... e6 for black, but that is just me.
Nobody seriously plays the Marshall defense as it's very bad, AiryNeon. You might want to reconsider that. After 3.cxd5 Nxd5 4.Nf3, Black is in trouble.
How is black in trouble?
Just 5... Nb6.
I usually play the Queens Gambit Refused: Marshall Defense (1. d4 d5 2. c4 Nc6)
That's not even the Marshall, it's the Tchigorin.
I usually play the Queens Gambit Refused: Marshall Defense (1. d4 d5 2. c4 Nc6)
That's not even the Marshall, it's the Tchigorin.
I meant 2... Nf6.
Did you need to see something like this?
I normally play the Grunfeld Defence.
However, I do like some lines in the Slav Defence which I do play from time to time if my opponents allows me to get into them.
The problem I have is I do not like all the lines of the Slav.
Which is why it is not my main defence.
I like specific lines; however, I can't really force myself in them lol.
The line I play is my own little pet line.
I have named the line The Slav Defence/ King's Variation.
Some of my chess friends have told me the line has a name already.
They said the name of the line is called The Slav Defence/ Schlechter Variation.
However, I do not believe this it true at all.
My line is like completely different.
If anything I would call my line The Slav Defence/ Schlechter Variation Improved.
or
The Slav Defence/ King's Variation
I think I prefer the name I have given it better.
a5.
My vote goes for the slav. Its super solid. Don't play that junk marshal defense shown above, it's terrible.
If none works, play dutch defense to 1.d4 :):)
I am just saying... Don't rage on me.
I am just saying... Don't rage on me.
I am sorry.
I wish the world was a nicer place.
I wish people could explain things so others could understand perfectly.
Sadly these wishes have not come true yet.
However, I believe one day they will.
The people on this forum are telling you not to play the Queens Gambit Refused: Marshall Defense.
I know perfectly well why they are telling you this.
They are telling you these things to try and change your path.
They are trying to put you on a better chess path.
However, the way they have done so has only caused you to strengthen your current direction.
Them telling you not to play it!
Them dismissing your analysis!
As only caused the line to become more mysterious and desirable to you.
In the end you will ignore what they are saying and you will play it regardless of what they say.
You will play it because it seems desirable and forbidden.
or
You will play it to prove them all wrong and be rebel-ish.
You see not everything in chess is black and white.
In the above position white has traded a flank pawn for a center pawn.
A Center pawn is thought to be more valueable than a Flank pawn.
Since, Black has played the move 2...Nf6 instead of 2...c6 or 2...e6.
Black will not be able to recapture the pawn on d5 with another pawn.
Thus, Black's center control has been reduced which is one of the reasons why this is thought to be good for white.
However, even though people have told you this and I have told you this.
I have a funny feeling your going to play it any way! 
With or with out other people's blessing.
Which brings us to an area in chess which I like to call "The Grey Area"
The Grey Area in chess is when a person choses to play something even if the line is unsound.
And that my friend is were I come in!
You see I am part of a secret society who are not afraid of playing an unsound or lost position.
We try to improve the lines and make them work or make them even better!
Which some would say is either a stroke of genius or a stroke of shear maddness!
Which is leading up to the point I am trying to make.
If you chose to play the Queens Gambit Refused: Marshall Defense.
Than allow me the privelage to introduce you to a line known as:
Doesn't it just give you chills!
OOOOOO sounds scary as well.
An if you are interested in this line.
You should check out the following link:
http://www.chess.com/forum/view/chess-openings/a-new-opening-the-infinity-gambit
You should also consider joining the group:
http://www.chess.com/groups/home/infinity-gambiteers
DUN DUN DUN!
Thank you. I plan to play this in my next fun game and I will probably adopt the line. 
Hi to everybody, my question is simple. I am looking for a strong defence to Queen's Gambit. (don't say Budapest Gambit please, i checked it out and didn't like it.)