I travel extensively in my business, can I deduct books, magazines, and movies as entertainment?

As long as they are related to the business...

You should look up the rules yourself on this. There are several different sets of rules for travel expenses, depending on how long you're gone, how you're reimbursed, how far away you travel, and where your primary place of work is at.

It's difficult to answer without knowing your circumstances.

Normally, entertainment is on you, but you're allowed certain things if you obey the rules, for example if you entertain clients while entertaining yourself, the rules are a lot less restrictive.

your business travel is deductible, but books, magazines, and movies for your own personal entertainment are not.
"entertainment" usually refers to entertaining a client for dinner, show, sports event, etc.
the basic rule is if its a business expense related to business it can usually be deducted. but the items you mentioned are more for personal enjoyment.