'source of illustration' is correct and usable in written English.
It refers to a source that is being used as an example for illustrative purposes. For example, "The author used a famous quote from Mahatma Gandhi as a source of illustration."
NEW YORK A credit for an illustration with the City Room column in some editions on Wednesday, about Juan Rodriguez, believed by some to have been the first non-Indian to settle in New York, included incorrect information from the New York Public Library's Schomburg Center for Research in Black Culture for the source of the illustration.
Jennifer Coggon and Mary P. Winsor contribute a charming essay about the path of their research into the source of the frontispiece illustration of On the Nature of Limbs.
Second is the surprise of finding no mention of that exhibition, despite its being the source of all four illustrations with the article.
Hence, living in a high SES area such as Burnside was not recognised as a source of anecdotes or illustrations relevant to 'the question'.
The authors of the article "The future of hybrid imaging part 3: PET/MR, small animal imaging and beyond", published in Insights Imaging (2011) 2 235 246 would like to point out that Fig. 6 was composed from several sources for the purposes of illustration.
(Here's an extreme and made-up example just for the sake of illustration: "Some sources believe that the earth is flat; others insist that it is round").
Also, for simplicity of illustration, we assume that each source has a distinct best relay.
Probably the best sources of medieval fashion illustration, as Mr. Wieck writes, are the calendars in prayer books; here, unconstrained by literature or history, medieval artists painted fashionable men and women of leisure.
Because of a captioning error by our photographic source, our illustration supposedly depicting the ivory-billed woodpecker (Dead or alive?, October 15th) actually shows the crimson-crested woodpecker.
