SPOHN, E. Vertical shaft furnaces for cement firing with conical shaped burning zones. Materiales de Construcción, [S. l.], n. 015, p. 12–14, 1950. DOI: 10.3989/mc.1950.i015.3110. Disponível em: https://materconstrucc.revistas.csic.es/index.php/materconstrucc/article/view/3110. Acesso em: 29 apr. 2024.