General Information
Note: several of these links focus on fiction writers. However, a lot of the information is applicable to all writers.
Poets & Writers comprehensive Guide
The Importance of Having an Agent
AgentQuery.com offers one of the largest searchable database of literary agents on the web—a treasure trove of reputable, established literary agents seeking writers.
Lists recent publishing deals. $25 monthly subscription or $10 day pass. Well worth the money, especially because you only need to pay month by month.
Nonfiction Literary Agents Open to Submissions
Note: this is from 2019 but may still be useful.
Searchable database. Look for instructions for how to search using Twitter hashtags.
Helpful article and resource list.
How to get a literary agent for nonfiction
Helpful article and resource list.
How to Write a Query Letter: Nonfiction and Memoir
Comnprehensive guide by Jane Friedman.
Guide from Agent Query
Robin Hershkowitz, Ph.D. 