"The Battle of the Super-Pets" reprinted from Action Comics #277
"The Bride of Mr. Mxyzptlk" reprinted from Action Comics #291
"Supergirl's Farewell to Earth" reprinted from Action Comics #258
"The War Between Supergirl and the Supermen Emergency Squad" reprinted from Action Comics #276
"Supergirl's Greatest Challenge" reprinted from Action Comics #287
This is G-57, G-56 is Our Army at War #203 and G-58 is Flash #187