Lapsoft Software and Systems
Offers Enhance23 add-in. Provides a FAQ and free download. Learning Lotus 1-2-3 Version 5.0 for Windows
Online tutorial from the Land Grant Training Alliance of North Dakota State University. Lotus 1-2-3
Official site. Part of the Lotus SmartSuite office suite. Spreadsheet World
Richard Warr's BackFour 1-2-3 file recovery (shareware) and Unseal password decoder (free), short Lotus FAQ.