Wright, H. Nelson, The Coinage and Metrology of the Sultans of Dehli, Oxford University Press, London, 1936, original printing, 432 pages, 23 plates, hardcover. Probably the best reference currently available on the Dehli Sultanate. It is in typical format with legends written out and interspered with discussions of metrology and other aspects of numismatic history. It includes the Ghorids. There are several plates of mediocre photos and many appendices with tables of ornaments, titles, legends, etc., ex The Skanda Collection Library.
Estimate: 50-75 USD