Lyon, W., & Duke, B. J. (1981). Introduction to human services. Reston Pub. Co.
Lua i Stíl Chicago (17ú heag.)Lyon, William, agus Bill J. Duke. Introduction to Human Services. Reston, Va: Reston Pub. Co, 1981.
Lua MLA (9ú heag.)Lyon, William, agus Bill J. Duke. Introduction to Human Services. Reston Pub. Co, 1981.
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