Powers, B., W., ,., M.(2008).Impressioning Compendium Espertise™ A guideline for excellent impressions in theory and practice (2008).Germany:St. Paul, MN, USA and Seefeld,.
Gaya MLA
Powers, Bernd, Wöstmann, ,John, M.."Impressioning Compendium Espertise™ A guideline for excellent impressions in theory and practice".2008Germany:St. Paul, MN, USA and Seefeld,,2008.Buku Pelajaran.