Canciones De Las Brigadas Internationales has been reprinted in a facsimile edition and is avalable from Amazon es. for 14,00 € Songs are in many languages including English https://www.amazon.es/Canciones-Las-Brigadas-Inter-Facs%C3%ADmiles/dp/8484723437
Also available on E Bay https://www.ebay.es/itm/154701592798
Or as an e-Book here for £2.40   https://books.google.co.uk/books/about/Canciones_de_las_Brigadas_Internacionale.html?id=QONMZ1p4ZJYC&redir_esc=y