The Nicaragua Study Group is publishing a second edition of the book Nicaragua to 1940: A Philatelic Handbook, by Clyde Maxwell. We were gifted ownership of this catalog in 2019 by previous owner Bill Byerley, who years ago bought the rights to the work from the widow of Clyde Maxwell.
So far, we have published in early 2020 the enlarged and improved second edition only as a draft e-book. It is in color and with images of real stamps. It might only ever be an e-book. The second edition retains Maxwell's valuations from 1988 (we are not all-knowing of what the stamps are worth, and it is too much work to try to keep up).
The second edition includes Maxwell catalog numbers and Gibbons catalog numbers (with the kind permission of Stanley Gibbons Ltd.) No Scott numbers -- Scott wanted too much money, and we would have had to jump through too many hoops on an annual basis.
I am the editor of the quarterly Nicarao and the editor of the second edition of Maxwell and the Nicaragua Study Group's secretary-treasurer.
All members have this draft e-book, and any new member will receive the draft e-book after joining the NSG. Dues are $10 for an e-mail subscription to Nicarao, $20 by postal mail to the USA, $22 by postal mail to Canada, and $25 by postal mail elsewhere. If paying by PayPal, those amounts are $10.75, $21.20, $23.30, or $26.50.
More information is at
http://www.bio-nica.info/nicarao/index.html