Carini A, Diligenti M, Maier G. Symmetric boundary integral formulations of transient heat conduction: saddle-point theorems for BE analysis and BE-FE coupling. Arch. Mech. 1997;49(2):253-283. Accessed January 17, 2026. http://am.ippt.gov.pl/index.php/am/article/view/v49p253