The links below to references in the literature which include analytical aspects of philately. These may be very important because the name of books and papers are often not indicative of details of their contents.
|Chun, Tham Yoke||Use of Phosphor in Singapore Stamps||Journal of the Singapore National Academy of Science 16, 1987 pp. 115-117|
|Liston, Edward M.||The 'China Clay' Variety of the 1908-1910 Washington-Franklin Issues?||Collectors Club Philatelist, Vol. 84(3) 2005 pp. 141-146|
|Liston, Edward M.||The "China Clay" Variety of the 1908-1910 Washington-Franklin Issue?||Collectors Club Philatelist, Vol. 84(2)2005. pp. 105-112|