(Divided by type of resource, but in no particular order because I didn’t have time to alphabetize by author’s last name. Also, many of these resources work for longer novels as well.)

Facebook Groups About Anthologies & Shared Worlds to Join:

Boxed Sets – Group for Authors

Boxed Sets Opportunities for Authors

Anthology/Boxed Set/Shared World Opportunities for Authors

TNRC Anthologies and Series

Books:

How to Write Short Stories and Use Them to Further Your Writing Career (Bell on Writing) by James Scott Bell

Creating Short Fiction by Damon Knight

How to Write Winning Short Stories: A practical guide to writing stories that win contests and get selected for publication by Nancy Sakaduski

Let’s Write a Short Story: How to Write and Submit a Short Story by Joe Bunting 

Writing Short Romance for Pleasure and Profit: How I Became a Six Figure Author Writing Short Romance by Sadie B. King

How To Write Short Romance: The quick and easy guide to writing Instalove by Nell Alexander 

Quickies: Writing Short Fiction for the Romance Market by Nancy Cassidy 

The Tropoholic’s Guide to External Romance (The Tropoholic’s Guides) by Cindy Dees

The Tropoholic’s Guide to Backstory Romance Tropes (The Tropoholic’s Guides) by Cindy Dees

The Tropoholic’s Guide to Internal Romance Tropes (The Tropoholic’s Guides) by Cindy Dees

7 FIGURE FICTION: How to Use Universal Fantasy to SELL Your Books to ANYONE (Universal Fantasy™: Butter Up Your Writing Book 1) by T. Taylor

The Universal Fantasy List: ROMANCE (Universal Fantasy™: Butter Up Your Writing Book 2) by T. Taylor

Romancing the Beat: Story Structure for Romance Novels by Gwen Hayes 

Articles:

Alicia Rasley’s Outline Your Novel in 30 Minutes Tool by Alicia Rasley

How to Write a Short Story by Rosemary Tantra Bensko and Sean Glatch

How to Write a Novella: Short, Sweet, and Sellable by Abi Wurdeman

5 Tips for Writing a Novella that Wows Readers by Sarah Skilton

4 Steps to Writing a Novella by Michelle Ule

How To Write A Novella by Eva Deverell

Novella Writing Guide: Tips, Techniques and Examples by Magda Wojcik

How to Write a Novella that Feels Like a Full Book by Melissa Tagg

When to Write a Novel vs. Novella: 3 Crucial Factors by Sarah Rexford 

How to Write a Short Story That Captivates Your Reader by Jerry B. Jenkins

How to Write a Novella: 7 Tips From an Expert by the Reedsy Editorial Team, edited by Tom Bromley

How to Write a Short Story by Jenn Ashworth

How to Write a Novella That Will Captivate Readers By Georgina Roy

How to Write a Short Story (Ultimate Guide + Templates) by Christopher Kokoski

Ten Tips for Writing Novellas by Dan Peacock

YouTube Videos:

How to Write a Novella by Reedsy 

How to Write a Novella by A.N. Sage

Stephen King on the Craft of Short Story Writing

Publishing 101: So You Want To Write A Short or Novella… by Christina C Jones

How to Write a Short Story in 6 Steps by Jerry B. Jenkins

How to Write a Short Story (with no experience) by Abbie Emmons

7 Easy Ways to Give Your Characters Instant Chemistry by Abbie Emmons

How to Instantly Give Your Characters Internal Conflict by Kate & Abbie Emmons