How can we track where the orders come from? Yes, we can track visitors and traffic by google analytics. But I don't know the original source of orders.

Can I create links such as

www.mysite.com/index.php?source=here
www.mysite.com/index.php?source=there

and then track the orders?

Thanks for your advice.

BTW, I just bought one coffer for zen-cart team, thanks for your efforts and great work.