A guide to more than 24, 000 national and international organizations, including: trade, business, and commercial, environmental and agricultural, legal, governmental, public administration, and military, engineering, technological, and natural and social sciences, educational, cultural, social welfare, health and medical, public affairs, fraternal, nationality, and ethnic, religious, veterans', hereditary, and patriotic, hobby and avocational, athletic and sports, labor unions, associations, and federations, chambers of commerce and trade and tourism, Greek letter and related organizations, and fan clubs.