php script billing receipt

Hi, I just finished a script for an US company and now have to provide them with a billing receipt stating my work and the price for it. google didn't come up with anything usefull, most search results came up with billing scripts and not an example text of such a billing receipt. Does anyone have an example text, which you use when you have to charge a client for your work? I am asking because english isn't my first language and instead of making s.th. up in my own words it would surely look better, if I can present s.th. which is 100% correct :) Thanks, Duncan