Damage necklace

Hello. Can anyone tell where this item actually drops? http://wotlk.openwow.com/item=43297
I tried to get atleast one neck, from the mobs with highest chance to drop. Killed like 400-500 of them. But not a single neck was dropped. Or i just have a bad luck? Or the data base is not correct ?
(sorry for my eng)

It's has a chance to drop off basically every trash mob in Northrend, for a while you could farm them off Naxx trash but the last good place that I knew of was Onslaught Harbor in Icecrown.