Wiki says spawns on the bridge of the Destroyer on top of the green console. It can also be found in the University's Auditorium in the left storeroom inside a metal cabinet. [don't have it myself, pls confirm]

Drop from the Infected Militia Scout (previously Infected Legendary Soldier). Spawns somewhere between Mansion, Junkyard and Volcano. Drops from the Infected NATO Pilot boss zombies found at Heli crashes and in the power building of Power Plant.

Blue Ridge has renovated the Middle Mountain Cabins to be their latest and greatest Brahmin pitstop, but they just can't seem to keep the local critters at bay. The Repeller Speaker system they use to repel the creatures and keep their Brahmin safe has been damaged. To retake the pitstop and create a safe haven for their Brahmin to rest, they will need your help! Clear out the creatures, defend the Repeller, and the Blue Ridge Caravan will reward you handsomely for your assistance!" [3]

Drops from the Infected "Rogue" (not from the blonde one though), who spawns at the very top of the hill next to Mines, in the area surrounding the motel. It's difficult being self-employed, it's not easy. It's important to get everything to balance," Nicholas said.Agree to wash his hat. Use the washtub (in with the appliances) and 7 ish Muscle, or S.I.T.'s steam laundry. Return the milkman's clean hat. Drops from the Infected "Snake" who spawns in the underground showers of prison, between wards A and B.