The Ladder of Expertise: Building a Chain of Resources from Popular to Expert

Scholarly/Expert Sources: peer-reviewed and (if book-length) subject to scholarly review after publication; based on original research and refer only to other expert sources; always cite their sources of data and opinion; follow discipline-enforced standards of analysis and rhetorical practice.  Intended audience: experts in the author's field.
Popular-Scholarly Sources: probably not peer-reviewed but authors are pre-qualified by professional reputation; responsible to editors and fact-checking departments with high emphasis on accuracy; usually summarize and build upon the work of other expert sources to make original contributions to the field, but rarely include original research; cite sources of most data and opinion; follow discipline-enforced standards of analysis and rhetorical practice.  Intended audience: experts in the author's field and those in related fields, as well as the post-secondary-educated general public.
Scholarly Print and Online Reference Sources: dictionaries that define terms used by scholars/experts; encyclopedias of concepts and persons relevant to the field; dictionaries in various languages; written by experts and supervised by senior scholars; subject to extensive review and fact-checking before publication; reviewed by scholarly reviewers; follow discipline-enforced standards of accuracy using rhetoric and vocabulary intended for student readers.  Intended audience: post-secondary students in the author's field.  (These are the most rarely used and the most powerful aids to the student writer seeking to step from popular to scholarly/expert sources.)
Popular Print Sources: never peer-reviewed; authors usually are journalists with B.A. or M.A./M.S. level experience in the field; responsible to editors and fact-checkers but errors are common and are corrected in subsequent editions; sometimes summarize expert sources and rarely speculate in original ways about consequences not mentioned by experts; follow current commercially successful standards of analysis and rhetorical practice.  Intended audience: the general public (reading vocabulary typically 9th to 10th grade).
Popular Online Sources: like popular print sources, but authors usually are unedited and nobody checks their facts; rarely draw their conclusions only from expert sources; repeat unprofessional speculation and gossip as fact; sometimes are not assigned a formally identified "author" at all (pseudonyms, web aliases, etc.); follow commercially successful or no standards of analysis and rhetorical practice.  Intended audience: fans, chance visitors from the general public (reading vocabulary varies but rarely above high-school).