In their Preface, the authors point out that “Learning Hypertext Markup Language (HTML) and Extensible Hypertext Markup Language (XHTML) is like learning any new language, computer or human” (Musciano and Kennedy xi).

In your Bibliography, or on your Works Cited page, you should list:

Musciano, Chuck, and Bill Kennedy. HTML and XHTML: The Definitive Guide. 4th ed. Sebastopol, CA: O’Reilly, 2000.

If you cite another paragraph from the same work, or if the author or authors are clearly indicated in your text, common sense suggests that you only need to add page number(s) for the citation. For example:
In their Preface, the authors point out that “Learning Hypertext Markup Language (HTML) and Extensible Hypertext Markup Language (XHTML) is like learning any new language, computer or human” (Musciano and Kennedy xi).

In your Bibliography, or on your Works Cited page, you should list:

Musciano, Chuck, and Bill Kennedy. HTML and XHTML: The Definitive Guide. 4th ed. Sebastopol, CA: O’Reilly, 2000.

If you cite another paragraph from the same work, or if the author or authors are clearly indicated in your text, common sense suggests that you only need to add page number(s) for the citation. For example: