I recommend [this](https://www.reddit.com/r/Stutter/comments/zh3ywn/comment/j141z7s/?utm_source=share&utm_medium=web2x&context=3) post from a PhD researcher and speech therapist. Regarding speech therapy - I have never applied it myself - but one of the biggest speech therapies based on research studies is in my opinion the Lidcombe stutter program. It's free of charge because the government pays for it and everyone worldwide can apply for the therapy. Among children, it has a pretty high percentage of people who outgrow stuttering, although, I argue that children without therapy have a greater chance to outgrow or spontaneously recover from stuttering. They offer a [free](https://www.uts.edu.au/sites/default/files/2020-07/Stuttering%20and%20its%20Treatment-Eleven%20Lectures%20%28May%202020%29.pdf) ebook with the latest results of different research studies.