Citation Hunt

The Wikipedia snippet below is not backed by a reliable source. Can you find one?

Click I got this! to go to Wikipedia and fix the snippet, or Next! to see another one. Good luck!

In page VisiCalc:

This text is part of the article's lead section, so referencing it may be optional. Please see WP:CITELEAD for more information.

"

VisiCalc ("visible calculator")[1] is the first spreadsheet computer program for personal computers,[2] originally released for the Apple II by VisiCorp on October 17, 1979.[1][3] It is considered the killer application for the Apple II,[4] turning the microcomputer from a hobby for computer enthusiasts into a serious business tool, and then prompting IBM to introduce the IBM PC two years later.[5] More than 700,000 copies were sold in six years, and up to 1 million copies over its history.[citation needed] [6]