Hein Online coverage varies most from volume 1 (pdfs of originals).
Library catalog, coverage varies, but for most have from volume 1 (Both print collections and validated online collections (like HeinOnline) are cataloged (and linked) at the level of the journal name, so a catalog search by journal title should work as a universal first step).
example citation: Jensen, Erik M., Under the Robes: A Judicial Right to Bare Arms (and Legs and …)?. Green Bag, 2d, Vol. 12, p. 221, 2009; Case Legal Studies Research Paper No. 09-7. Available at SSRN: http://ssrn.com/abstract=1353388.