Stiel, H., & Collins, D. (1994). Ultimate service: The complete handbook to the world of the concierge. Prentice-Hall/Career & Technology.
Chicago-viite (17. p.)Stiel, Holly, ja Delta Collins. Ultimate Service: The Complete Handbook to the World of the Concierge. Englewood Cliffs, N.J: Prentice-Hall/Career & Technology, 1994.
MLA-viite (9. p.)Stiel, Holly, ja Delta Collins. Ultimate Service: The Complete Handbook to the World of the Concierge. Prentice-Hall/Career & Technology, 1994.
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