Zook, C. (2004). Beyond the Core: Expand Your Market without Abandoning Your Roots. Harvard Business Review Press.
Lua i Stíl Chicago (17ú heag.)Zook, Chris. Beyond the Core: Expand Your Market Without Abandoning Your Roots. Boston, Massachesutts: Harvard Business Review Press, 2004.
Lua MLA (9ú heag.)Zook, Chris. Beyond the Core: Expand Your Market Without Abandoning Your Roots. Harvard Business Review Press, 2004.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.