A.L. Besse,
Einstein Manifolds,
Ergeb. Math. Grenzgeb. (3), {\bf 10}, Springer-Verlag, 1987.
S.K. Donaldson,
Yang--Mills invariants of smooth four-manifolds, (Donaldson's trick)
Geometry of low-dimensional manifolds (S.K. Donaldson, C.B. Thomas, eds.), Vol. 1.
Cambridge University Press, Cambridge (1990), 5--40.
A. Degtyarev, I. Itenberg, V. Kharlamov,
Real Enriques Surfaces,
Lect. Notes in Math. 1746 (2000).
Daniel Huybrechts,
Moduli spaces of hyperk\"ahler manifolds and mirror symmetry,
math.AG/0210219.
Alex Degtyarev, Ilia Itenberg, and Viatcheslav Kharlamov,
Finiteness and quasi-simplicity for symmetric K3-surfaces,
Duke Math. J. 122, Number 1 (2004), 1-49.