GIL-MUGARZA, G. Letters and numbers. Spanish book production in the twentieth century through the statistical sources. Revista de Historia Industrial — Industrial History Review, [S. l.], v. 23, n. 56, p. 151–187, 2018. Disponível em: https://revistes.ub.edu/index.php/HistoriaIndustrial/article/view/21112. Acesso em: 13 feb. 2025.