Technical Illustrators.org Forum

Where do you guys get contacts from? I'm putting together a list of all the companies I would like to try and work with and it's hard to find a contact name or department name for many of them.
Would you send things to an art director, marketing manager, product manager?
Can you call up the companies and find out who to contact?
What do you do?
thanks!

I'm finding this very difficult as well. I have yet to get the book (once I can afford it), but my instructor in class mentioned the Artists and Graphic Designer's Market book. There is a 2010 edition out now and evidently in it companies post contacts for illustrators to get a hold of them. It varies for each field of illustration so I've yet to see if it has anything for us Technical Illustrators. Anyone else heard of this book? Do you know if there are contacts listed for us in it? Something I'd be curious to know.