“…Substrates, the medium upon which a document is created, cover a vast range, including but not limited to traditional paper, man-made substrates such as polymers and stone-papers, as well as mirrors, blackboards, and walls. Two textbooks [ 521 , 522 ], 13 articles [ [523] , [524] , [525] , [526] , [527] , [528] , [529] , [530] , [531] , [532] , [533] , [534] , [535] ], 12 conference presentations [ [536] , [537] , [538] , [539] , [540] , [541] , [542] , [543] , [544] , [545] , [546] , [547] ] had substrates as their subject in this period of review.…”