The problems in perspective, by G.B. de Huszar.
The geographical problem, by C.C. Colby.
The historical problem, by Avery Craven.
The ethnological problem, by Robert Redfield.
The economic problem, by Jacob Viner.
The sociological problem, by W.F. Ogburn.
The legal problem, by Quincy Wright.
The educational problem, by R.J. Havighurst.
The psychological problem, by David Slight.
The philosophic problem, by Richard McKeon.
The religious problem, by J.L. Adams