Question: Who wrote the book on which a musical was based which featured the song She Used to Be Mine?
Related documents: [0]  [DOC] Waitress is a musical with music and lyrics by Sara Bareilles, and a book by Jessie Nelson. Based on the 2007 film of the same name, written by Adrienne Shelly, the musical tells the story of Jenna Hunterson, a waitress in an unhappy marriage to her husband Earl. When Jenna unexpectedly becomes pregnant she begins an affair with her gynecologist Dr. Jim Pomatter. Looking for ways out she sees a pie contest and its grand prize as her chance. [END] 
[1]  [DOC] "She Used to Be Mine" is a song written and recorded by American singer-songwriter Sara Bareilles for her fifth studio album, "" (2015), featuring songs from her stage adaptation of the 2007 film, "Waitress". It was released to digital retailers as the lead single on September 25, 2015. [END] 
Answer: 
Jessie Nelson
Jessie Nelson