2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/77974We first classify the possible configurations of fibrations which are not semi-stable on extremal elliptic K3 surfaces. Then we give a complete list of extremal elliptic K3 surfaces whose singular fibers are all not of type $I_n$.15pages, 2figuresAlgebraic Geometry14J28; 14J27text