Gunton, George
Appelton and Company , 1899
Buku Teks
Hirst, Francis W.
E.P. Dutton & Co , 1906
Buku Teks
Davira Rizky Chairunnisa, author
Fakultas Ekonomi dan Bisnis Universitas Indonesia, 2019
UI - Makalah dan Kertas Kerja
Todd, Paul, author
London : Balckstone, 1994,
Buku Referensi
Scott, Austin Wakeman, 1884-1981, author
Little, Brown, 1963
Buku Teks