Do you have customers that will pass out your books to their friends, family or co-workers? Will they pick up all the orders for their office when they pick up thier order? Do any of the offices that you sell at have a "contact person" (usually a receptionist) that everyone leaves their checks with, and that you leave everyones order with?

Ask them to be your helper. They are already helping and with a little incentive they may be able to help you to substantially increase your order totals.