A good friend just came back from India with a couple of pounds of those thick copper coins called "dumps."  I don't know why they're called dumps.  Certainly they don't call them that in India.  But the term is used by Western numismatists to denote thick Indian coppers, just as the term "cob" denotes for us, and for us alone, the handmade Spanish colonial gold and silver.
    Indian coins have always been somewhat difficult to get outside of India.  The export laws, while not totally prohibitory, have been complex and difficult.  India is a giant country, and there is two and a half millennia of numismata, so there has always been "a lot" of it around, but in relation to how much is actually available, not so much.  The export laws have been liberalized somewhat in recent years, but this occurred simultaneously with a significant growth in coin collecting within India itself, so that actually today there are fewer Indian coins available on the world market today than a decade ago.
    The result of this dearth, in personal terms, is that I have a waiting list for interesting Indian coins whenever I get some in.  I don't have to attribute them.  I can just mark them up and ship them out.
    But I'm like everyone else in the numismatic world - I want to know what I'm looking at.  Maybe there's some new item, never before noticed.  So I got out my books and while the family was watching the tube I began to scratch my head over these coins.
    I studied Arabic and Persian for a year and a half in college, and I've been fooling around with Indian coins for 30-odd years, and let me tell you, they are hard!  Those die sinkers had some cute conventions, such as breaking up the word order and even the words.  They left out letters too.  It's as if, on American coins, they wrote out the legend like: "Of States Unied Am The Erica".  And the dies are ALWAYS too large for the planchet, so some of the legend is ALWAYS missing.  The missing part usually contains the mint and/or date, which is a constant heartache if you care about those things.
    Given that all the dies are handmade, there may be dozens of varieties for any given issue, and the style of the calligraphy can vary wildly.  It's just hard, hard, hard to figure out some of these coins.  Even though I can pick out some of the words (or pieces of words) I find myself drifting back to the picture catalogs.
    So what do I use for references?  The Krause books of course.  More than anything else because they're available, but their (partial) listings of Mughal (the dynasty that built the Taj Mahal, whose rulers struck at hundreds of mints) dates and mints are unique and of exceeding value.  Not too many photos of copper dumps in them though, so some frustration thereby engendered.
    I also use Michael Mitchiner's "Oriental Coins and their Values, Vol. 1 - The World of Islam."  This book is a 500 page survey of Islamic coinage from its beginning to the present.  There is a thick Indian section with a lot of photos.  Some of the pictures are not too clear however.  The big problem with this book is it's out of print.  When available it goes for upwards of $300.00 these days.
    Then there's W. H. Valentine's "Copper Coins of India," a 1914 work reprinted in 1977.  It's very incomplete, and I don't like the organization at all, but there are more than 800 very clear line drawings of copper coins.  And, most important, IT IS AVAILABLE.