Google’s design and technical guidelines

Google’s quality guidelines

Google’s webmaster guidelines

Google’s SEOs information

Google sitemaps

Yahoo! Search Content Quality Guidelines

Yahoo! Tips on how do I improve the ranking of my web site in the search results?

MSN’s Guidelines for successful indexing

Lycos Workshops Search Engine Optimization

https://seochat.com

https://searchenginewatch.com

https://webworkshop.net

https://en.wikipedia.org/wiki/Search_engine_optimization