Hi Thomas,
Thank you for citing our software in your work and congratulations on your PhD!
We have included some examples below depending on the requirements of the journal.
If you are citing within the text:
DataGraph (Version 4.6) Visual Data Tools, Inc. Chapel Hill, NC. https://www.visualdatatools.com/
Here is one example using APA style guide for a reference list:
Visual DataTools, Inc. (2020). DataGraph (Version 4.6) [Computer software]. https://www.visualdatatools.com/
If you are adding a general statement:
The data analysis and graphics were generated using DataGraph, Version 4.6. Copyright © 2020 Visual Data Tools, Inc., Chapel Hill, NC, USA. Available at: https://www.visualdatatools.com/
If you need to cite a document:
Adalsteinsson D., and P. Schultz. The DataGraph Manual, (2020) Version 4.6, Visual Data Tools, Inc. Chapel Hill, NC. https://www.visualdatatools.com/DataGraph/Manual.pdf