Berets and Book Covers

I came upon this book 'Unlikely Warriors - the British in the Spanish Civil War and the Struggle against Fascism'; the cover photo triggering a search for SCW books with berets on their cover. 

And there are many, no surprise, like Hemingway's 'Second War, bearing Witness to the SCW'.

And 'Comrades and Commissars', by Cecil B. Eby. 

Robert Capa's 'Heart of Spain,

and 'Wales and the Spanish Civil War' by Robert Stradling. 

Or 'Heroic Voices, Memories from the International Brigades', by Peter Darman

Many are the berets on books about "The good cause".