Possible Clues:

• AMA and ABA, e.g.
• Charitable gps.
• E-mail address endings, sometimes
• Groups: Abbr
• Trade grps.
• Assocs.
• NATO and OAS
• NATO and PLO, for two
• A.A.A. and B.B.B., e.g.
• N.A.A.C.P. and others