The UVic Writer's Guide
If the author of the software is not named, the title of the software is placed first and underlined, followed by the label "computer software," the name of the supplier, and the year of issue or copyright:
MultiMate Advantage II, computer software, MultiMate International Corporation, 1987, version 1.0.
A "knowledge base" is an electronic source of information. It may be a computer program or an on-line service. Follow the rules for books or for a section of a book if the author is known, or for anonymous books if not. The version number takes the place of the edition.
Best, Michael. Shakespeare's Life and Times. Version 1.1. Intellimation: Santa Barbara, CA: 1991.
Gurr, Andrew. "The Globe Theatre Site." SHAKSPER Global Electronic Conference, SHAKSPER@utoronto.bitnet. January, 1991.