Performance investigation of formed tubes of different geometry for a Flat-plate solar collector. International Journal of Current Engineering and Technology, [S. l.], v. 1, n. 5.Special Issue, p. 273–278, 2016. Disponível em: https://ijcet.evegenis.org/index.php/ijcet/article/view/4301. Acesso em: 27 jul. 2026.