Willem van der Molen
When dad and mom are away from home... panji paniba 11.20-45
Fakultas Ilmu Pengetahuan dan Budaya Universitas Indonesia, 2021
 Artikel Jurnal
Maxwell, John C.
How to lead when your boss can't (or won't) = Cara mengambil alih peran kepemimpinan
MIC, 2020
 Buku Teks
Zemke, Ron
E-Service : 24 ways to keep your customers-when the competition is just a click away
Amacom, 2000
 Buku Teks
Burton, Hester
Castors away! / Hester Burton
Oxford University Press , 1962
 Buku Teks
Hudson, W.H.
Far away and long ago
New York E.P. Dutton & Co 1947
 Buku Teks