Deletion of Working in layers

Comment: as the nominator does not appear to have read or understood the article.  It explains that "in the early 15th century Cennino D'Andrea Cennini describes how to paint in layers" and so there's an authoritative source in plain sight.  It is, of course, easy to find modern sources which confirm this such as the ''https://books.google.co.uk/books?id=mkJfbdTS--UC&pg=PA422 Grove Encyclopedia of Materials and Techniques in Art''.  The nominator also does not seem to understand  which only requires citations for quotations and controversial material
Stance: keep
Cited policy: Wikipedia:Verifiability (WP:V)