The automorphism groups of certain singular K3 surfaces and an Enriques surface

We present finite sets of generators of the full automorphism groups of three singular K3 surfaces, on which the alternating group of degree 6 acts symplectically. We also present a finite set of generators of the full automorphism group of an associated Enriques surface, on which the Mathieu group M_{10} acts.
Comment: 41 pages, 1 figure, typos are corrected, references are updated