If you are serious about your genealogy, you will find the book Evidence Explained, by Elizabeth Shown Mills to be the absolute authority on source and citation issues.
Now this book is available as a digital download, making it available wherever your research takes you. To learn more about this offering, check out her website at: https://www.evidenceexplained.com/
I also recommend that you create a free account on the website and view the information in the forums. Some of the most respected minds in genealogy are available to answer and discuss your questions.