The Civil service year book 1989
England. Cabinet Office
Her Majesty's Stationery Office, 1989
 Buku Referensi
The hospitals and health services year book 1989
editor, NW Chaplin
The Ynstitute of Health Services Management, 1989
 Buku Referensi
Sri Mulat Yuningsih
Kondisi kualitas data debit sungai tahun 2015-2016 di Indonesia
Kementerian Pekerjaan Umum dan Perumahan Rakyat, 2019
 Artikel Jurnal
The British year book of international law 1989 : sixtieth year of issue
Clarendon Press, 1990
 Buku Referensi
The Computer users year book 1989 : supplier guide, volume 4
VNU Business Publications, 1989
 Buku Referensi