SAN FRANCISCO -- Google on Thursday made its version of communally-constructed online encyclopedia Wikipedia multi-lingual, opening its Knol compendium to nuggets of knowledge shared in French, Italian or German.

The Internet search powerhouse is inviting people to submit written "knols," to indicate units of knowledge, in those languages as well as in English.

Google's free Knol service has floundered since its July launch and international contributors could help it better compete with Wikipedia, which is consistently ranked among the most visited websites on the Internet.

"Our goal is to encourage people who know a particular subject to write an authoritative article about it," Google vice president of engineering Udi Manber said at the unveiling of the Knol service.

"There are millions of people who possess useful knowledge that they would love to share, and there are billions of people who can benefit from it."

While Wikipedia lets visitors make changes to its online pages, trusting that people with accurate information will correct errors and misleading entries, Google invites folks to author their own articles.

Pictures of authors are displayed on their knol web pages. Editorial responsibility rests with authors, whose reputations are at stake, according to Manber.

While Wikipedia merges topic entries in single articles, knols written on the same subjects remain separate and "compete" for the attention of visitors, who can give online feedback.

Knol authors have the option of letting Google post ads on their pages and sharing in the revenues.

Google is the world's most used Internet search engine and a proven master at mining revenue from online advertising targeted at those making queries and using its free Web-based services.

Luring Wikipedia users to its own community-created online encyclopedia promises to be another rich vein of ad income for the US Internet search giant.