Formula That Finds Info On A Different File?

Hello,
I'll try to explain this the best I can being a kind of newbie to excel formulas.
I currently am using a file that gives me dates of store openings. Easy.
The only problem is that We keep having to send out new files to all the employees with the updated dates. Is there a way that everyone can use their main file with the formulas but get the information off of a single file with all the dates from a common network drive that they all have access too? I wanna be able to update the file and just save it and have everyone always be using the most current dates.
The problem is that there are to many updates and its to much of a hassle sending out new files out every couple weeks.
Thanks in advance for your help.
Nate

Or what about having one file and make it public to everyone? Is it possible to make a file unsavable or completly uneditable?
Nate