word choice - Use of definite article in cross-references

When referencing a chapter or section in a book, when should I use "the" in front of them?

For example, considering the sentences:

(The) Chapter 5 presents X and Y.

or

X, detailed in (the) Chapter 5, is Y.

or

X, detailed in (the) Chapter 5 of this book, is Y.

I would not use "the" in the second example, but not using it in the third one seems rather unnatural for me, although English is not my native language.

What are the grammar rule(s) in English concerning the use of the definite article in cross-references? I could not extrapolate this case from existing SE questions or from online English references.