Many of our customers have special billing requirements, and we will prepare our invoices accordingly. Some of your billing options are: Invoices can be listed alphabetically by either author or title. Invoices can be separated by purchase order number, by fund number, or both. Invoices can be subtotaled by purchase order number or fund number. If individual order slips are numbered, we can print these numbers on the invoice. Invoices will be supplied in the appropriate number of copies. We can group and bill special funds separately. We can send invoices with shipments or separately through the mail. We can prepare voucher forms, if needed, to your special requirements. Electronic invoices are available for some acquisitions systems. If you have any special billing requirements, just let us know.