Where can I find the Vault-Tec lab coat?

The Fallout wiki lists this apparel item as being in the dockhouse south of the Harbormaster hotel. I think I found the place (with a dead brahmin outside) but its suitcase contains a Postman Uniform. Where can I find this +2 INT coat?

Edit: I also checked Vault 111 again and you cannot loot the skeletons or overseer—they just have an "Activate" function and your character says that everyone is dead. I didn't see the lab coat anywhere else there.

Solution 1:

The Cambridge polymer labs and vault 81 contains guaranteed lab coats.

Just be aware there are quests in both locations that you must start before you are able to access the area with the lab coats.

Solution 2:

You can come to the settlement called "Covenant".

After your investigation there, you come to the "Covenant Compound". While clearing it you will find a lot of Vault-tec lab coats.

It is part of the mission "The Human Error".