Books that go into detail on how to speak well?

Books that go into detail on how to speak well? I used to have a massive stuttering problem that I have now greatly reduced thanks to therapy and practice. I do not stutter in front of friends and family at all now. I'm am able to have conversations one on one with new people I have met. However I struggle greatly with speaking in class without useing long pauses and a lots of "likes" in place of my stammer. These stammers come out whenever I am anxious which usually happens if I have to talk in front of a lot of people or if the person I am talking to is being aggressive. I also have difficulty starting conversations with authority figures, in particular male authority figures like some professors. Are there any books that can help me learn to talk clearly whenever I want?