Marsh 1st edition, has the essential information, and not much more. I gather that the 2nd & 3rd editions, which I haven't seen, have a lot more.
I live 3,000 km from a coin shop, so I get my coin books from the Internet. I find that once I decide what to buy, then I research what is available, from where, what price. Then I watch eBay, so that when something I want is available, I know whether I'm getting a good price.
I've seen second-hand books on eBay fetch 50% more than new books on Amazon, presumably because bidders didn't do basic research.
Anyway, I have compiled this list of books available on sovereigns: the only one I've seen is Marsh's ist edition, which I have at home. I don't regard it as a "great" book, but as an adequate reference.
The History of the Gold Sovereign
by Sir Geoffery Duveen & H. G. STRIDE
[HGS was former Chief Clerk of the Royal Mint
1st edition published 1962, Oxford Uni Press
The History of the British Sovereign
By J. J. Cullimore ALLEN, 1965
SOVEREIGNS OF THE BRITISH EMPIRE
by J. J. CULLIMORE ALLEN
Publisher: SPINK SON LTD (1965) Hardcover: 60 pages
*** I'm not sure if the above really are two separate books - same author, same year. But I've seen references with the two titles, above. I've noted them both, for the sake of completeness.
The Gold Sovereign.
Michael A Marsh
Published by Cambridge Coins 1980. First Edition. Hardback in dustwrapper with gilt titling and decorations. 72 pages, illustrated.
The Sovereign. The World's Most Famous Gold Coin. A History and Guide
by Daniel Fearon and Brian Reeds, 2001, 80 pages,
well illustrated in color throughout, large format, maroon cloth, dust jacket.
"THE GOLD SOVEREIGN", by Michael A. Marsh. Golden Jubilee [3rd] Edition, 2002.
The standard catalogue of gold sovereigns with great detail and beautiful illustrations.
126 pages, with many illustrations.
The Sovereign - The World's Most Famous Coin - A History and Price Guide.
Authors: James Mackay, Daniel Fearon and Brian Reeds
? date; Publisher: Hilden Publications; 80 Pages.
Marsh has also written about the half-sovereign.
General books often have a lot to say about sovereigns:
Seaby's Standard Catalogue of British Coins, Coins of England and the United Kingdom,
16th edn 1978
29th edition 1994
34th edition 1999
I gather that this is now published under the name "Spink's".
The Gold Coins of England
By R. L. KENYON
Renniks'; and MacDonald's catalogues deal with Australian sovereigns.
Of course, there are well known catalogues by Krause
; several of which tell some part of the sovereign story.
Peter in Oz