Never Close Another Order
You Don't Need Closing Skills If…
"I have a lot of quotes out there. My next step is to close them."
Your next step is to learn how to properly sell print such that it eliminates the "close" step entirely.
To close an order means to convince a customer to accept your price and your terms. Negotiation is involved. Conflict, too. And probably concession. Selling on price leads to this end and if that's the case, then yes, you do need to learn how to close and there are plenty of books on that subject.
Backup the sales process to the beginning and take a different path. Instead of looking at their print needs and asking the question, "Do you have anything I can quote on?" seek to understand their business needs and come up with a print solution. Not only does this get you engaged at a different level (read: Decision-maker), and not only does this mean you are competing on the basis of your idea and not your price, this eliminates the need to close the order because if you've done your job correctly, you will be awarded the job without ever bidding against someone else.
So, you don't need closing skills if you up your sales game and learn to solve problems.