Finding Other Books Like Yours for Giveaways

Hello to everyone from a new Library Thing member. Hope you are all well.
I wondered, if you write cross-genre as I do, how you compare your work to other books?
i.e. When offering my novels as a giveaway, Library Thing wanted three books they were similar to. Which flummoxed me.
Many thanks & happy writing,
Marni

Not to be snide, but this is an important thing to know for a lot of aspects of book marketing. Aren't there any books that might not be EXACTLY like yours, but similar in setting, mood, or type of plot? Aren't you a reader as well as a writer?

My most-difficult-to-categorize book is the Erotopharmakohymnia, which I wrote in the obsolete genre of ludibria. Needing to pigeonhole it for self-publishing on Amazon, I chose "Occult Fiction" and "Hermeticism & Rosicrucianism" on the basis of the categories of books that had inspired me, and ones where I thought readers would have a relevant interest.