Prefacing remarks 1. With the exception of synthetic cannabinoids and cannabimimetics, all references are subdivided by individual drug, drug group/class, or general topic, then chronologically (year only) within each subsection, then alphabetically by first author within each year. Synthetic cannabinoids and cannabimimetics are in a separate category (1.D), and are subdivided as individual compounds, groups of compounds, and finally as groups with other drugs. 2. Some citations included in this report are dated prior to June of 2019, because they had not yet been abstracted prior to the 2019 report. 3. All citations are formatted in accordance with Uniform Requirements for Manuscripts Submitted to Biomedical Journals. 4. No restricted articles are cited in this report.