irule to permit url by external host,

Doh. What I get for typing on an iPad. Please try this:

when HTTP_REQUEST {     
    if { ( [string tolower [HTTP::uri]] starts_with "/books" ) } {
        if { not ( [IP::addr [IP::client_addr] equals "55.66.77.88"] ) or not ( [IP::addr [IP::client_addr] equals "66.77.88.99"] ) or not ( [IP::addr [IP::client_addr] equals "77.88.99.10"] ) } { 
            HTTP::redirect "https://[HTTP::host]/" 
        }
    }
}    

I was still missing a closing parentheses.

Also FYI, this ltm is located on a DMZ, the client IP are external from the Internet..would it even show up?

This is a good question. Are you evaluating IP addresses that would show up at the F5?

I would also add, that if you're going to be evaluating more than 3 source addresses, tiny could ninja's data group idea would probably be easier to maintain, at least with just an address data group.