• 55 Ecosystem management
• 52 History
• 48 Human geography
• 35 Description and travel
• 28 Travel
• 28 Voyages and travels
• 27 Natural resources
• 26 Human ecology
• 24 Historical geology
• 24 Marine biology
• 24 Social life and customs
• 21 Ecology
• 21 Environmental aspects
• 21 Plate tectonics
• 20 Biotic communities
• 20 Geology
• 20 Study and teaching
• 19 Social ecology
• 18 Cultural geography
• 17 Geomorphology
• 17 Hydrology
• 17 Water
• 16 Biosphere
• 15 International economic relations

• 336 Films Media Group
• 43 American Public Television
• 39 555 Productions, Inc
• 24 Infobase
• 21 BBC Worldwide Ltd
• 20 Canamedia (Firm)
• 18 Public Broadcasting Service (U.S.)
• 14 Cambridge Educational (Firm)
• 14 National Geographic Television & Film
• 11 Electric Sky (Firm)
• 11 German United Distributors
• 10 Agency for Instructional Technology
• 8 Allegro Productions (Firm)
• 6 Looking Glass Pictures
• 5 Granada Media (Firm)
• 5 Tele Images Creations (Firm)
• 4 Ampersand Film & Video Tape Productions
• 4 Parthenon Entertainment (Firm)
• 4 Uniview Worldwide
• 3 Academic Media (Firm)
• 3 Content Media Corporation
• 3 Driscoll, Emily V
• 3 Journeyman Pictures (Firm)
• 3 Network Ireland Television

• 334 English
• 15 Spanish
• 1 Multiple languages

• 61 Europe
• 30 Latin America
• 27 South America
• 24 Asia
• 17 Central America
• 16 Earth (Planet)
• 16 India
• 15 Africa
• 15 United States
• 14 North America
• 13 Middle East
• 12 South Asia
• 12 Southeast Asia
• 9 China
• 8 Africa, Sub-Saharan
• 5 Mexico
• 4 Japan
• 3 Arabian Peninsula
• 3 Australia
• 3 Egypt
• 3 Hawaii
• 3 Mekong River
• 3 Nicaragua
• 3 Oceania
• 3 Wales

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