Operational calculus based on the two-sided Laplace integral / Balth. van der Pol and H. Bremmer. Pol, Balthasar van der, 1889-1959. Bremmer, H., 1904- joint author. Calculus, Operational. QA432 .P67 1955 517 POO Includes index. Cambridge [Eng.] : University Press, 1955. 1955. 1955 Text 415 p. : eng