APA 6th Edition:
* Retrieval Information: Generally didn't include retrieval information (like a DOI or URL) unless the book was accessed online. If it *was* online, the URL would be included.
* Edition: If it was not the first edition, "ed." followed the title (e.g., *Title of book, 2nd ed.*).
* DOI/URL: Only included if the book was accessed online.
APA 7th Edition:
* Retrieval Information: Always includes retrieval information, prioritizing DOIs. If a DOI is unavailable, then a URL is used. If neither is available, this information is omitted.
* Edition: The edition number is now written out as "2nd edition," "3rd edition," etc., instead of using "ed."
* DOI/URL: Always included if available, regardless of access method (print or online). If a DOI exists, that's prioritized over a URL.
Example (Illustrative - Check APA Manual for Nuances):
Let's say we're citing the same book:
Author, A. A. (Year). *Title of book*. Publisher.
APA 6th Edition (Print):
Author, A. A. (2020). *Title of book*. Publisher.
APA 6th Edition (Online):
Author, A. A. (2020). *Title of book*. Publisher. Retrieved from [URL]
APA 7th Edition (Print & Online):
Author, A. A. (2020). *Title of book*. Publisher. https://doi.org/xxxxxxxxx *(or URL if no DOI)*
In short: The most significant change is the consistent inclusion of retrieval information (DOI or URL) in APA 7th edition, regardless of the access method. The formatting of edition numbers also differs. Always consult the official APA Style Manual for the most accurate and up-to-date guidelines.