Re: What is this?! (Wikipedia article based Daito Ryu book)
Further info: (The following is an excerpt from the publisher's response when I queried them last year about the validity of the Aikido book)
"The mentioned text was published under the so called "GNU license" at Wikipedia. This was the free decision of the authors.
Any licensee - also a publishing house - who adheres to the terms and conditions is given permission to modify the work, as well as to copy and redistribute the work or any derivative version, also for commercial reasons.
According to the GNU license it is not required to inform the author or to obtain the authorīs approval.
If the licensee wants to mention some of the authors the licensee has to take exactly the names given by the authors at Wikipedia: this might be the real name, a pseudonym, nonsense or whatever."