There are many free resources available in electronic format. It is important to remember to look for scholarly materials. Check for author credentials and look for the source of the resource. Items listed here will be Open Access materials, Open Educational Resources, and Public Domain materials. These terms are defined as follows:
Open access (OA) refers to freely available, digital, online information. Open access scholarly literature is free of charge and often carries less restrictive copyright and licensing barriers than traditionally published works, for both the users and the authors.
While OA is a newer form of scholarly publishing, many OA journals comply with well-established peer-review processes and maintain high publishing standards.
This work is licensed under a Creative Commons Attribution 4.0 International License.from Cornell University Library
As defined by UNESCO, Open Educational Resources (OER) are learning, teaching and research materials in any format and medium that reside in the public domain or are under copyright that have been released under an open license, that permit no-cost access, re-use, re-purpose, adaptation and redistribution by others. (Recommendation on open educational resources (Oer) | unesco. (n.d.). Retrieved May 3, 2023, from https://www.unesco.org/en/legal-affairs/recommendation-open-educational-resources-oer)
According to the Copyrightlaws.com, "the phrase "public domain" (PD) isn't in the U.S. Copyright Act. It is, however, commonly used to refer to content that isn't protected by copyright law.
Works that are in the public domain may be used freely, without obtaining permission from or compensating the copyright owner."
(Editor, C. com. (2023, March 7). What is the public domain? Copyrightlaws.Com: Copyright Courses and Education in Plain English. https://www.copyrightlaws.com/what-is-the-public-domain/)