Citations of: Łos J.. On the extending of models . Fundamenta mathematicae, vol. 42 , pp. 38–54.Łos J. and Suszko R.. On the extending of models . Common extensions. Fundamenta mathematicae, vol. 42 , pp. 343–347.Słomiński J.. On the extending of models . Extensions in equationally definable classes of algebras. Fundamenta mathematicae, vol. 43 , pp. 69–76.Łos J. and Suszko R.. On the extending of models . Infinite sums of models. Fundamenta mathematicae, vol. 44 , pp. 52–60