Gaya APA
Black, C, /, H, E.
(1968).
Twentieth century Europe: a history.
.
New York:
New York Alfred A Knopf.
Gaya MLA
Black, C.E., /, Helmreich,, E.C..
"Twentieth century Europe: a history. ".
New York:
New York Alfred A Knopf,
1968.
Buku.