Stock Illustration Source/Images.com now represents the visual content of Encyclopaedia Britannica. (Disclosure: SIS, a trademark of Images.com, is part of the same group of companies and is under the same ownership as Selling Stock and MediaPost Communications.) Founded in 1768, Encyclopaedia Britannica has amassed a diverse library of reference, education and learning materials on scientific, artistic and historic subjects. Its visual offering ranges from hand-drawn illustrations to the latest in digital art.