Annex F (informative) Core undefined behavior [ub]

F.3 [expr]: Expressions [ub.expr]

F.3.4[ub:expr.type.reference.lifetime]
Specified in: [expr.type]

Evaluating a reference when an equivalent use of a pointer denoting the same object would be invalid has undefined behavior.
[Example 1: void g() { int* ip = new int(5); int& i = *ip; delete ip; i; // undefined behavior } — end example]