At this rate, probably the GhostBusters.

It’s late. I need to send a proposal out tomorrow. The price sheet I’ve got doesn’t have the price of the equipment I need. There’s no contact information for the guy, or his company in the price-sheet. I’m not expecting an immediate response, it’s the middle of the night, but I can’t even send him an email (hoping he’ll deal with it early tomorrow morning). Worse, I’ve already wasted half an hour just looking for his details and trying to remember where I might have kept any of his contact details. Even if it did have the price, I still have no idea how I’d buy the stuff from him – I can’t reach him.

I’ve said it lots of times, and I’ll probably keep saying it till I’m blue in the face.
Put your contact details on everything you produce.

I can’t buy anything from you if I can’t find you.
Nor can any other prospective client.