. Retrieved 2007-05-09. ^ Hansell, Saul (June 3, 2007). "Google Keeps Tweaking Its Search Engine" . New York Times . http://www.nytimes.com/2007/06/03/business/yourmoney/03google.html . Retrieved 2007-06-06. ^ Danny Sullivan (September 29, 2005). "Rundown On Search Ranking Factors" . Search Engine Watch . http://blog.searchenginewatch.com/blog/050929-072711 . Retrieved 2007-05-08. ^ "Search Engine Ranking Factors V2" . SEOmoz.org.