Rathinasamy, Elan (2016年9月29日). “Penguin 4.0 - How Devaluing Differs From Demoting”. TechWyse. 2017年8月25日閲覧。 “In short, it can be considered as good news for webmasters who aren’t deviating from Google’s guidelines, particularly those that have spam links built by their competition in order to demote their site.”