Spencer, D. (1963). English for proficiency. Oxford University Pr.
Chicago-čujuhus (17. p.)Spencer, D.H. English for Proficiency. London: Oxford University Pr, 1963.
MLA-čujuhus (9. p.)Spencer, D.H. English for Proficiency. Oxford University Pr, 1963.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.