If an expression initially has the type “reference to T” ([dcl.ref], [dcl.init.ref]), the type is adjusted to T prior to any further analysis.
The expression designates the object or function denoted by the reference, and the expression is an lvalue or an xvalue, depending on the expression.

- [expr.type] p1

To me it seems like this paragraph could be a note, because it doesn't provide any normative information. This paragraph does not state what kind of references are turned into lvlaues or xvalues respectively, it merely hints to the reader that such a conversion mechanism exists.

All the specifics can be found in other paragraphs, such as:

• [expr.call] p13 for function calls
• [expr.static.cast] p1 for static_cast
• ...