He drew on the material for a series of books that have remained essential reading for musicians and scholars.
As they nearly always do, the boycott-and-ignore lobby brought the book fantastic publicity, it sold in the hundreds of thousands and has remained essential reading ever since.
Still, cash has remained essential in certain instances, like paying back a colleague for lunch, buying fruit at a farmers' market or buying a beer at a cash-only bar.
Since time immemorial, forests and their associated products have remained essential in sustaining livelihoods (Mamo et al. 2007; Bwalya 2013; Mukul et al. 2016), particularly for the people of forest-dependent communities, who live in abject poverty (Shackleton et al. 2007; Kabubo-Mariara 2013).
Rather he had concluded ("Essay on the Development of Doctrine," 1845) that Catholicism had remained true to what was essential precisely by its power of changing.
Until last week, his generosity had not extended to the "Bridge of Friendship," the main link with Afghanistan, which had remained closed to all traffic -- including essential food shipments.
Extracting practical size subsets for experimentation has remained an essential step in the design of combinatorial libraries.
Two decades ago, a mathematician named Andrew Hodges published "Alan Turing: The Enigma," which is one of the finest scientific biographies ever written, and has remained an essential resource for all subsequent accounts of Turing's life.
But behind those details was a portrait of a genius, a book that since its publication in 1971 has remained an essential study of a founding father of modern theater.
It explains why The Moscow Times has remained an essential newspaper not just for Moscow's foreign community of diplomats, business people, students and journalists, but also for many independent-minded Russians.
