The free online resource Wikipedia is about as accurate on science as the Encyclopedia Britannica, a study shows.
The British journal Nature examined a range of scientific entries on both works of reference and found few differences in accuracy.
Wikipedia is based on wikis, open-source software which lets anyone fiddle with a webpage, anyone reading a subject entry can disagree, edit, add, delete, or replace the entry. It relies on 13,000 volunteer contributors, many of whom are experts in a particular field, to edit previously submitted articles.
But it has been criticised for the correctness of entries, most recently over the biography of prominent US journalist John Seigenthaler.
The web encyclopedia has responded to the criticisms by tightening up procedures.
Next month it plans to begin testing a new mechanism for reviewing the accuracy of its articles.
Wikipedia was founded in 2001 and has since grown to more than 1.8 million articles in 200 languages. Some 800,000 entries are in English.