"Membership clubs" include country clubs, golf clubs, social clubs and the generic term "private clubs."
Books on club management: The Club Managers Association of America produces books and sells them through their MarketPlace (online book store), including the general Your Club and the Law. The National Club Association also has an Online Store, with a general book called The Legal Reference Guide for Private Clubs.
Conferences: The National Club Association and the Club Managers' Association of America host national and regional conferences. Critenden hosts a major Golf Conference.
Law Firms: Golf, Inc. does a survey to identify the top law firms for club-related work. In 2011 the winners were Addison Law, Foley & Lardner and Troutman Sanders.
Legal materials: I have not found much written for lawyers representing membership clubs, other than the stray article posted online (usually by another lawyer). The materials written about business law, employment law and real estate development may be your best for resources. See also the "Books" section, above, and the section on "Trade Journals," below.
Trade Journals: Trade journals include Board Room Magazine (a/k/a The Boardroom), the Private Club Advisor, Club Management by the Club Managers Association of America and Club Director by the National Club Association. Crittenden's Golf Business & Real Estate "delivers the inside information on development, sales and financing for golf courses."
A consultancy called McGladry posts a series of articles on their Private Club Resources page.