Skurzynski, G. (1981). Safeguarding the land. Harcourt Brace Jovanovich.
Cita Chicago (17th ed.)Skurzynski, Gloria. Safeguarding the Land. Harcourt Brace Jovanovich, 1981.
Cita MLA (9th ed.)Skurzynski, Gloria. Safeguarding the Land. Harcourt Brace Jovanovich, 1981.
Atenció: Aquestes cites poden no estar 100% correctes.