There are many different styles for citing references, and you should follow those in use at your university or institution, or required by the publication. Surfer and Golden Software can be cited when the software is first mentioned and in the bibliography or reference list.
If you want to simply reference it in the body of the paper, you can use "Surfer® from Golden Software, LLC (www.goldensoftware.com)" or "Surfer® (Golden Software, LLC)". Surfer is a registered trademark, and so it has an ® after it.
If you want to reference it at the end in a bibliography or reference list, our information is:
Golden Software, LLC.
809 14th Street
Golden, Colorado 80401
Updated October 16, 2018