Restatements are published by the American Law Institute. The Institute consists of some 4000 lawyers, judges, and law professors. The online edition has "links to cases" citing the Restatment.
Westlaw: Home > Secondary Sources > Restatements & Principles of the Law > The Law Governing Lawyers
Technicaly, American Law Reports (ALR) has both primary and secondary sources of material. It higlights representative cases and then annotates them with commentary and cross references. If there is one on your topic, it's a goldmine of information.
WestLaw: Home > Secondary Sources > American Law Reports
Select either the Digest or the Index and look for "Attorney." For example:
West: Home > Secondary Sources > Texts & Treatises
Recommended by class text: Legal Malpractice by Ronald E. Mallen and Allison Martin Rhodes (last updatd Jan. 2015)
Here are a few examples of potential sources for specialty practice. See also p. 47-48 of your text.
Legal Ethics in a nutshell, Ronald D. Rotunda & Michael I. Krauss. St. Paul, MN :Thomson/West, 2006 UMKC Law Library KF306. Z9 R668 2006 (latest version is 2013, which is on order by the library). Now available on West Academic Study Aides along with many other resources (if the link does not respond go to the library databases page).
Legal Ethics : A Legal Resource Guide, Lee F. Peoples, Buffalo, NY : W.S. Hein, 2006 UMKC Law Library KF306 .P46 2006
Legal Ethics : A Comparative Study, Geoffrey C. Hazard & Angelo Dondi, Stanford Cal., Standord Univ. Press, 2004 K123 .H39 2004