How do you make reference to "previous month" in a Blogger template?

For the life of me, I can’t figure this out, and can’t find the answer anywhere.

At the bottom of my weblog and each of its individual archived months, I want to make a reference to the previous month. For example, on the July 2004 page, I want the bottom to have a link to the June 2004 page, and so on. How can I do this? I can’t seem to find a blogger tag that does this.