Interactive Fiction Database

Killworth, Peter. How to Write Adventure Games for the BBC Microcomputer Model B.  Chapter 8.

Nelson, Graham. The Inform Designer’s Manual. Fourth edition. Chapter 7. Copyright 2001.  Available as an open source, free PDF at http://inform-fiction.org/manual/DM4.pdf

Wood, John. “Player Character Identity in IF.” XYZZYnews 9. Issue 3.    http://www.xyzzynews.com/s-title.html