List all the names of people in this paragraph.  Separate the names with commas.
When Guettel took up music composition in his mid-teens, he was encouraged by his family. His mother said that she offered him advice for around a year, "After that, he was so far beyond anything I could ever have dreamed of, I just backed off." Richard Rodgers, who died when Guettel was 15, overheard an early composition, said he liked it and asked him to play it louder. Guettel has qualified the compliment, noting that "He was literally on his deathbed on the other side of the living-room wall." In his high school and collegiate years and into his early twenties, Guettel worked as a rock and jazz musician, singing and playing bass, before realizing "that writing for character and telling stories through music was something that I really loved to do, and that allowed me to express love."
Guettel, Richard Rodgers
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When Guettel took up music composition in his mid-teens, he was encouraged by his family. His mother said that she offered him advice for around a year, "After that, he was so far beyond anything I could ever have dreamed of, I just backed off." Richard Rodgers, who died when Guettel was 15, overheard an early composition, said he liked it and asked him to play it louder. Guettel has qualified the compliment, noting that "He was literally on his deathbed on the other side of the living-room wall." In his high school and collegiate years and into his early twenties, Guettel worked as a rock and jazz musician, singing and playing bass, before realizing "that writing for character and telling stories through music was something that I really loved to do, and that allowed me to express love."
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Answer the following query.
List all the names of people in this paragraph.  Separate the names with commas.

user
Guettel, Richard Rodgers
assistant