Links with GET requests

Using the Validator on some of my scripts used to return an error
because I was using a "?variable=value&variable2=value" GET request in a
link. I changed it from & to &&; and it seems to work but I'm wondering
if there is a nicer way to create the & in the URIs without using &&;.
Using &&; works but really doesn't look nice at all and I think it's
against some standard or another.