I've written a few chapters of a book. Should I send it to a literary agent?

We don't give out advice, but here are some professionals whose blogs and books about book publishing etc. we recommend:

http://help.leanpub.com/en/articles/2272256-resources-for-learning-how-to-improve-your-ebook-s-discoverability-and-improve-your-self-publishing-skills

Please note that Leanpub is a self-publishing platform that is primarily devoted to encouraging people to publish their books while they are still in-progress. You can create a book anytime here:

https://leanpub.com/create/book
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Here are some tips we give to people who publish on our platform:

http://help.leanpub.com/en/articles/1587118-tips-for-self-publishing-and-selling-books-using-leanpub

And if you really want to go deep into our publishing philosophy, here's our manifesto:

https://leanpub.com/lean

Good luck on your writing journey!