Sezon 11
Bölümler
1 "The Last Stand: Western Mountain Parks" 2 Kas 1970 2 "The Last Stand: The Everglades of Florida" 9 Kas 1970 3 The Last Stand: Point Pelee 16 Kas 1970 4 The Last Stand: The Southwestern Desert 23 Kas 1970 5 A Sense Of Time: The Age Of The Universe 7 Ara 1970 6 A Sense Of Time: The Age Of The Earth 14 Ara 1970 7 A Sense Of Time: The Age Of Man 21 Ara 1970 8 The Great Lakes 1 Şub 1971 9 The Great Lakes 8 Şub 1971 10 Population Problems: Everybody'S Baby 15 Şub 1971 11 Population Problems: Tomorrow'S Child 1 Mar 1971 12 Who Help Themselves 15 Mar 1971 13 Psychiatry: Heavy Night 22 Mar 1971 14 Psychiatry: Street Fighting Mad 29 Mar 1971 15 Psychiatry: Human Potential 5 Nis 1971