Publisher and Publication Date: Ballantine Books. Paperback published December 3, 2019.
Genre: Historical fiction.
Pages: 384.
Source: Self-purchase.
Audience: Historical fiction readers. Readers who want to read the background story of the book and film, The Wizard of Oz.
Rating: Good.
Britannica link for L. Frank Baum
Biography on L. Frank Baum
The Wonderful Wizard of Oz, a link at Britannica

L. Frank Baum (1856-1919)

Frank and Maud Baum in Egypt (1906)
Maud Gage Baum (1861-1953)
I’ve searched her name. She has a Wikipedia bio but she is not on Britannica.
Summary:
Finding Dorothy is about the wife of L. Frank Baum. Maud Gage Baum found out in 1938 that Hollywood was making a film about her late husband’s book, The Wonderful Wizard of Oz. She worked hard at trying to get on to the set of the film so she can make sure the film is true to what her husband had written. Maud was a formidable woman. She had tenacity and a keen eye. She didn’t take a closed door as a no. She also took under her wing, Judy Garland. She had empathy for the young starlet.
I was drawn to the book because I love the film, The Wizard of Oz. I also enjoy reading about Judy Garland. I love to hear her sing. I love to watch other films she made. I thought the book was about Judy Garland or the film, because of the title. I was mistaken. The book, Finding Dorothy, is about the life of Maud Gage Baum; and, secondly, it is about the book and film, followed by Judy Garland.
The book goes back and forth in time. Beginning in 1871; and, also in 1938. In the year 1871, Maud is a young girl in New York state. This is where her life picks up. Maud will reflect back on life before marrying Frank Baum, their married life, and the years the film was made (1938-1939.)

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My Thoughts:
As I’d shared under the summary, I’m disappointed the book was more about Maud Baum. I wanted to read a book about the making of the film, The Wizard of Oz, and about Judy Garland who was cast as Dorothy. However, I understand from reading Finding Dorothy how Frank Baum came up with the creative ideas for the books. There is actually a total of 43, plus a few that are Oz related. I’ve not read any of the books. I found, way back on my Kindle list of books, the first book in the series.
My favorite parts in the book is Maud’s observations of Judy Garland. Maud is the fly (so to speak) in the room watching the filming of scenes. Maud has reservations about Judy’s age, but when she hears the voice of Judy singing, Over the Rainbow, her opinion changes. Through Maud’s observations, I see the affects on Judy from what the studio groomed her to be. She was a young girl with a big voice. She had a talent that the industry swept down on like vultures. They saw big money. And, her mother didn’t help.
Letts’ gave a strong and vivid picture of Judy as an innocent, doe-eyed beauty.
In Maud’s life story, I learned about culture and standards for women during the late 1800s. Maud’s mother was a suffragette. She worked tirelessly to gain the ability for women to vote. Maud was a woman with strong opinions and she voiced them. Many women in this era kept their mouths closed.