APA-ийн эшлэл(7 дахь хэвлэлт)
ebrary, Inc, Gutzman, A. D., Muller, A., Pfledderer, D., & Gibbons, T. (2002). Buyers' guide to search engine optimization firms: Who should you hire? how much should you pay? (2nd ed.). MarketingSherpa.
Чикаго-гийн эшлэл (17 дахь хэвлэлт)
ebrary, Inc, Alexis D. Gutzman, Anthony Muller, Donna Pfledderer, ба Tim Gibbons. Buyers' Guide to Search Engine Optimization Firms: Who Should You Hire? How Much Should You Pay? 2nd ed. Portsmouth, R.I.: MarketingSherpa, 2002.
MLA -ийн эшлэл (9 дэх хэвлэлт)
ebrary, Inc, et al. Buyers' Guide to Search Engine Optimization Firms: Who Should You Hire? How Much Should You Pay? 2nd ed. MarketingSherpa, 2002.
Анхааруулга: Эдгээр ишлэлүүд үргэлж 100% үнэн зөв биш байж магадгүй.