(2002). Buyers' guide to search engine optimization firms: Who should you hire? how much should you pay? (2nd ed.). MarketingSherpa.
Chicago-Zitierstil (17. Ausg.)Buyers' Guide to Search Engine Optimization Firms: Who Should You Hire? How Much Should You Pay? 2nd ed. Portsmouth, R.I: MarketingSherpa, 2002.
MLA-Zitierstil (9. Ausg.)Buyers' Guide to Search Engine Optimization Firms: Who Should You Hire? How Much Should You Pay? 2nd ed. MarketingSherpa, 2002.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.