PERČIN, Ante; NAĐ, Ivan. Certificate for the implementation of private protection of critical infrastructure – a new level and quality or just a new form for providing private protection services. Crisis Management Days, Velika Gorica, Croatia, 2026. Disponível em: https://ojs.vvg.hr/index.php/DKU/article/view/835. Acesso em: 1 may. 2026.