OLDENBURGER, Jesper; THEUNISSEN, Bert. Alexander Numan (1780-1852) en de veredeling van de Nederlandse schapenrassen. Studium, Amsterdam, v. 8, n. 2, p. 65–83, 2015. DOI: 10.18352/studium.10108. Disponível em: https://platform.openjournals.nl/studium/article/view/20371.. Acesso em: 10 dec. 2025.