Gaya APA
Cloke, M., Wallace, R. (1974).
The Moedern Business Letter Writer's Manual (Trawas) .
Surabaya:
dolphin books.
Gaya MLA
Cloke, Marjane., Wallace, Robert.
"The Moedern Business Letter Writer's Manual (Trawas)".
Surabaya:
dolphin books,
1974.
Text.