According to the Iowa Core's Guide to Creating Text Sets:
A text set is a collection of related texts organized around a unit topic, theme, concept, or idea. The set is focused on an anchor text--a rich, complex, grade-level text. The anchor text is the focus of a close reading with instructional supports. The number of texts in a set can vary depending on purpose and resource availability around a given topic. What is important is that the text in the set are connected meaningfully to each other to deepen student understanding of the anchor text. In a sense, the text need to "talk to one another" so that in reading the set, students build a coherent body of knowledge around a topic.
This is not a complete list...search text set in the library's catalog for more.
Hoch, M. L., McCarty, R., Gurvitz, D., & Sikoski, I. (2019). Five key principles: Guided inquiry with multimodal text sets. Reading Teacher, 72(6), 701-710. http://odinproxy04.odin.nodak.edu/login?url=https://search.ebscohost.com/login.aspx?direct=true&db=eric&AN=EJ1213667&site=ehost-live
Kimmel, S.C. & Carlone, H.B. (2018) Three bags full: Integrating text sets with engineering explorations for young children. Science Activities, 55(1/2), 58-67. http://odinproxy04.odin.nodak.edu/login?url=https://search.ebscohost.com/login.aspx?direct=true&db=tfh&AN=135413167&site=ehost-live
Lewis, W. & Walpole, S. (2016) Designing your own text sets. Literacy Today, 33(4), 34-35. http://odinproxy04.odin.nodak.edu/login?url=https://search.ebscohost.com/login.aspx?direct=true&db=tfh&AN=112081840&site=ehost-live
Lupo, S.M., Berry, A., Thacker, E., Sawyer, A., & Merritt, J. (2020) Rethinking text sets to support knowledge building and interdisciplinary learning. Reading Teacher, 73(4), 513-524. http://odinproxy04.odin.nodak.edu/login?url=https://search.ebscohost.com/login.aspx?direct=true&db=tfh&AN=140917316&site=ehost-live