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References without attribution (ex. 5.1) refer to the Sun SCJP description.
Other references are listed here. My main study guide was [CJ2] which is a thorough treatment with good exercises and sample questions.

[JLS] Java Language Specification 3.0 the Java Language Specification, Third Edition, defines the Java programming language. I leave this open on my desktop while I am studying.

[API] Java API documentation. the Java 2 Standard Edition API documentation.

Between [JLS] and [API] that is all the information necessary to pass the exam, in theory. Working with the language is needed to develop the proficiency necessary to pass the exam. Hence, the need for study guides and tutorials.

[CJ2] Complete Java 2 Certification