Gaya APA
Xu, Li-Qun. (1992).
A New Method of Calibrating and Applying the Gravity Model .
:
s.n..
Gaya Chicago
Xu, Li-Qun.
A New Method of Calibrating and Applying the Gravity Model.
:
s.n.,
1992.
Computer Software.
Gaya MLA
Xu, Li-Qun.
A New Method of Calibrating and Applying the Gravity Model.
:
s.n.,
1992.
Computer Software.
Gaya Turabian
Xu, Li-Qun.
A New Method of Calibrating and Applying the Gravity Model.
:
s.n.,
1992.
Computer Software.