Revised language to indicate a better definition of secondary sources. Specifically, secondary sources do not exclusively draw on primary sources (this is reflected by the replacement of "primary sources" with "research and references"), and some secondary sources are created as an overview of a topic (many mass-market books and textbooks as examples).
Offered an explanation as to why secondary sources are preferable, based on the long-running discussion.
Addressed concerns repeatedly expressed in the long-running discussion about bias in secondary sources.
The usefulness of summary sources is mentioned to address the only well-expressed concern about tertiary source deprecation.
