What are the definition of pronouns
according to google
if the authors last name was in the text then you should still cite them. you should always cite them even if they were already mentioned.
in his "letter from a birmingham jail", martin luther king jr. resort to socrates to highlight his practice of a fair form of civil disobedience and non violence, as a symbol or analogy to back up his interjection outlining the urge of awakening from the "dark depths of prejudice and racism" of society at that time.