The older theory of the paradoxical effect of stim meds making ADHD people more "relaxed" is giving way to more specific theories so terms change. The term "calm" is not a medical or diagnostic term so things like "reduced hyperacitvity" or "increased focus" are used in the truly authorative peer reviewed published studies.
Here are all the medical consensus' for stimulant use for ADHD:
http://www.help4adhd.org/en/about/science
Try a search using the word paradoxical, adhd, stiumulant etc and look for things older than 2006. I pulled a few that use the word "calm":
http://www.hhmi.org/news/caron2.html
http://info.med.yale.edu/chldstdy/plomdevelop/genetics/01feb gen.htm
http://csl.georgetown.edu/info_packets/ADHDparentsheet.shtml
You might also contact CHADD to get help finding more.