Online encyclopaedia Wikipedia has tightened its submission rules following a complaint. Prominent journalist John Seigenthaler described as "false and malicious" an entry on Wikipedia implicating him in the Kennedy assassinations.
When he phoned Jimmy Wales, Wikipedia's founder, he was told there was no way of finding out who wrote the entry.
Wikipedia has since removed the entry and now requires users to register before they can create articles.
But visitors to the site will still be able to edit content already posted without having to register.
The case has highlighted once again the problem of publishing information online.
Unlike content published in magazines, books or newspapers, online information can be posted anonymously by anyone.
Wikipedia has thrived on offering people the chance to contribute to a collective knowledge bank.
Since its launch in 2001, Wikipedia has gathered together some 850,000 articles in English as well as entries in at least eight other languages on a wide range of topics.
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 volunteers, many of whom are experts in a particular field, to edit previously submitted articles.
Mr Wales acknowledged that the new procedures would not prevent people from posting false information but said he hoped it would limit the number of new articles being created.
This, in turn, should make it easier for the 600 volunteers to edit content, he said.
"In many cases the types of things we see going on are impulse vandalism," he said.
In an opinion piece for the USA Today, where Mr Seigenthaler was the founding editorial director, the 78-year-old journalist claimed that only one sentence in his Wikipedia biography was correct - the fact that he was Robert Kennedy's administrative assistant in the early 1960s.
He went on to describe Wikipedia as a "flawed and irresponsible research tool".
"The marketplace of ideas ultimately will take care of the problem but in the meantime, what happens to people like me?" he asked.
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