KNORTH, Erik J. In Memoriam: Joop Hellendoorn (1939-2025). Jeugd in Ontwikkeling , [S. l.], 2025. DOI: 10.54447/JiO.21875. Disponível em: https://testplatform.openjournals.nl/jeugdinontwikkeling/article/view/21875. Acesso em: 11 apr. 2026.