Wright, H. Nelson, The Coinage and Metrology of the Sultans of Dehli, Originally published by Oxford University Press, London, 1936, reprint by Oriental Books Reprint Corporation, New Dehli, 1974, 428 pages, 24 plates, hardcover with dust jacket. 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 James Farr Collection Library.
Estimate: 10-20 USD