APA Style
Gruen, Erich S.. ().
United States and Canada .
:
.
Chicago Style
Gruen, Erich S..
United States and Canada.
:
,
.
.
MLA Style
Gruen, Erich S..
United States and Canada.
:
,
.
.
Turabian Style
Gruen, Erich S..
United States and Canada.
:
,
.
.