Voight, R. C. (1971). Invitation to learning: The learning center handbook. Acropolis Books.
Chicago-čujuhus (17. p.)Voight, Ralph Claude. Invitation to Learning: The Learning Center Handbook. Washington: Acropolis Books, 1971.
MLA-čujuhus (9. p.)Voight, Ralph Claude. Invitation to Learning: The Learning Center Handbook. Acropolis Books, 1971.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.