Writers who used Greek and Latin literature to perfect their literary forms belonged to the Neoclassical Realism Classical period of literature.

The answer to this is 'neoclassical' period of literature. Writers who used Greek and Latin literature to perfect their literary forms belonged to the Neoclassical period of literature. Those who used Realism didn't put much romanticizing in their works; Those who had their works in the Classical period were the references of those writers in the Neoclassical era.