I've been addressing this in my college courses this year by assigning annotated bibliographies. This allows students to learn a new type of writing- annotate bibliographies, practice proper citation formatting (either APA or MLA), and evaluate sources on multiple levels.
CCSS.ELA-Literacy.W.11-12.8 Gather relevant information from multiple authoritative print and digital sources, using advanced searches effectively; assess the strengths and limitations of each source in terms of the task, purpose, and audience; integrate information into the text selectively to maintain the flow of ideas, avoiding plagiarism and over-reliance on any one source and following a standard format for citation (corestandards.org).
To this end I have created an assignment sheet, rubrics, and sample annotations in the MLA style for teachers in high school and college. This may also be appropriate in the middle school classroom.
How do you help your students address these standards?