Umar Adisubroto
Whale shark in the development of geopark and sustainable tourism in Gorontalo, Indonesia
Badan Perencanaan Pembangunan Nasional (BAPPENAS), 2021
 Artikel Jurnal
Conrad, Joseph, 1857-1924
Heart of darkness : authoritative text, backgrounds and contexts, criticism
W.W. Norton, 1971
 Buku Teks
Conrad, Joseph, 1857-1924
Heart of darkness : an authoritative text, backgrounds and sources, criticism
WW Norton , 1971
 Buku Teks
Trainor, F. R.
Introductory phycology / F. R. Trainor
John Wiley & Sons, 1978
 Buku Teks
Scott, F. R.
Events and signals / F. R. Scott
The Ryerson Press, 1954
 Buku Teks