Covey, S. R. (1991). Principle-Centred Leadership. Pocket Books.
Chicago-čujuhus (17. p.)Covey, Stephen R. Principle-Centred Leadership. London: Pocket Books, 1991.
MLA-čujuhus (9. p.)Covey, Stephen R. Principle-Centred Leadership. Pocket Books, 1991.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.