“Mary Wells: The Tumultuous Life of Motown's First Superstar” by Peter Benjaminson is an extremely well researched book that looks at the life and career of Mary Wells.
Of course we remember her huge singles in particular “My Guy” written and produced by Smokey Robinson in 1964.

We also remember that she was the first Motown act to tour internationally in 1964 at the request of the Beatles, who invited her to join them on a UK tour that year.
Sometimes being the first is a blessing and a curse - as she indeed laid the groundwork for the Supremes and Martha and the Vandellas etc to follow in her footsteps and achieve worldwide acclaim - especially in the UK.
She was a songwriter as well as a talented singer - and it was her efforts as a singer songwriter that got her signed to Motown at aged 17.
However - it was the contract she signed at this age that eventually led her to leave Motown in 1965 - as she was unable to renegotiate with more favorable terms.
Indeed part of the terms of the agreement of her release was that she could not receive any royalties from her past works with the label.
In 1965 she could not have know the enduring longevity and popularity of her Motown recordings - and spent the rest of her career trying to recapture that early success.
What is apparent is she played a huge role in making Motown a successful and very profitable label.
Check out this excellent book and let’s not forget about the life and impact of Mary Wells in popular music too!
More info here:
https://www.amazon.com/Mary-Wells-Tumultuous-Motowns-Superstar/dp/1613734867