Koolhaas, Rem
Elements
Venice, Marsilio
Buku Referensi
Bowman, Joel P.
Effective business correspondence
Harper & Row, 1979
Buku Referensi
Spinoza, Benedict de
On the improvement of the understanding : The ethics ; Correspondence
Dover, 1955
Buku Teks SO
Wildermuth, J.R.
English hotel correspondence
Ecole Hotellere, 1978
Buku Teks SO
Bouwens, C.
English Commercial correspondence
Persatuan Tenaga, 1957
Buku Teks SO