Sheppard, H. L. (1977). The graying of working America. The Free Press.
Cita Chicago (17th ed.)Sheppard, Harold L. The Graying of Working America. The Free Press, 1977.
Cita MLA (9th ed.)Sheppard, Harold L. The Graying of Working America. The Free Press, 1977.
Atenció: Aquestes cites poden no estar 100% correctes.