Hofstadter, Douglas R., 1945-
Metamagical themas: questing for the essence of mind and pattern
Basic Books, 1985
 Buku Teks SO
Niles, Mary Cushing
The essence of management
Harper & Brothers, 1958
 Buku Teks
Parkinson, Cyril Northcote, 1909-1993
The essence of managment
Federal Publications, [Date of publication not identified]
 Buku Teks
Huxley, Aldous
Ape and essence
Bantam, 1958
 Buku Teks
Walters, John
The essence of Buddhism
Thomas Y. Crowell, 1964
 Buku Teks