| 1940 - 444 стор.
A monthly magazine of political science and industrial progress. | |
| 1939 - 402 стор.
A monthly magazine of political science and industrial progress. | |
| 1936 - 396 стор.
A monthly magazine of political science and industrial progress. | |
| 1934 - 374 стор.
A monthly magazine of political science and industrial progress. | |
| 1933 - 386 стор.
A monthly magazine of political science and industrial progress. | |
| 1931 - 648 стор.
A monthly magazine of political science and industrial progress. | |
| 1930 - 718 стор.
A monthly magazine of political science and industrial progress. | |
| 1929 - 708 стор.
A monthly magazine of political science and industrial progress. | |
| |