Walton, L. R. (1988). How you can live six extra years. Woodbridge Press.
Cita Chicago (17th ed.)Walton, Lewis R. How You Can Live Six Extra Years. Woodbridge Press, 1988.
Cita MLA (9th ed.)Walton, Lewis R. How You Can Live Six Extra Years. Woodbridge Press, 1988.
Atenció: Aquestes cites poden no estar 100% correctes.