34 27. NONCOMPACT GRADIENT RICCI SOLITONS
§5. Theorem 27.46 is in [53]. Their proof is based on the earlier work in [16]
and [425], among others.
Theorem 27.50 is in [265] (see Theorem 1.4(2) in [267] for a generalization).
Theorem 27.51 is in [170].
§6. Theorem 27.53 is Proposition 1.1 in [280]. Its proof is a modification of an
idea of Perelman (see Proposition 9.81 in [77]). Theorem 27.54 was proved in [53].