Call of Duty: Black Ops Easter Egg - Sgt Roebuck Is Back!!!!!! and COD 5 Mission References

To find this awesome easter egg you must unlock the zombie level "FIVE," and when you start go to the left where the zombies break through the wall and look at the pictures. You'll find a picture saying "Sgt. Roebuck" and the other pictures are of missions of Call Of Duty World at War