. . "Logic." . . "Logique symbolique et mathématique." . . "Logik." . . . . . . . . . . . . . . . . . . "The Problems of Logic"@en . . . . . . "The Problems of logic, by Andrew Paul Ushenko" . . . "The problems of logic" . . "The problems of logic"@en . . . "The problem of logic"@en . . . . . . . "Logic, Symbolic and mathematical." . . "Logique." . . "Lógica." . . "Logica." .