One point of correction -- D.C. Fontana didn't "only help out on two Season 3 episodes," and without credit. She wrote the story and teleplay for 'The Enterprise Incident.' She received story credit for 'That Which Survives' (from her outline, "Survival') and 'The Way to Eden' (from her outline and teleplay, 'Joanna'). In both of those cases, though, she was unhappy with how she was rewritten, and she opted to use her pseudonym, Michael Richards (I've read that she wanted to use her pseudonym on 'The Enterprise Incident,' too, but Roddenberry talked her out of it).