Ratri Candra Restuti
Tingkat daya tarik objek wisata alam di Kabupaten Kebumen = Attraction level of natural tourist resorts in Kebumen Regency
Universitas Indonesia, 2008
 UI - Skripsi Open
Nature writing : the tradition in English
edited by Robert Finch and John Elder
W.W. Norton, 2002
 Buku Teks
Quammen, David
Natural acts : a sidelong view of science and nature
Schocken Books , 1985
 Buku Teks
Morrison, Tony
The Andes
Time-Life Books, 1975
 Buku Teks SO
Ley, Willy
Engineers' dreams/by Willy ley
The Viking Press, 1954
 Buku Teks