HAMMERICH, Helge. J. Johnston: Statistical Cost Analysis. Economic Handbook Series. McGraw Hill Book Company. New York 1960. Ledelse og Erhvervsøkonomi, [S. l.], v. 26, 1962. Disponível em: https://tidsskrift.dk/ledelseogerhvervsoekonomi/article/view/33952. Acesso em: 6 dec. 2025.