If Wikipedia is mentioned, that suffices to add the link; it doesn't matter if the link has dropped off the bottom of the page. Just keep mentioning Wikipedia!
Linux Today (http://linuxtoday.com/news_story.php3?ltsn=2001-09-25-010-20-PS)
MetaFilter (http://www.metafilter.com/comments.mefi/10939) and [1] (http://www.metafilter.com/comments.mefi/11256) and [2] (http://www.metafilter.com/comments.mefi/12025) and [3] (http://www.metafilter.com/mefi/12325)
... the splitting of water, leading to a net production of O2, ATP, and NADPH with the consumption of solar photons and water.
The Calvin cycle
The Calvin cycle is similar ...