:: Indeed, I agree that Challenger is a reliable source and have no dramas with the work (have only skimmed it to date though). However, as it has not been used as a reference for this article the work should only be added to the Further reading section, which I have done. If you would like to use Challenger to add more infomation to the article please do so with inline citations and then move the work to the References section. Cheers.