Gaya APA
SIANIPAR, M, O, C. (2013).
Impromptu speaking by lectures of english and indonesia .
Medan:
Universitas HKBP Nommensen.
Gaya MLA
SIANIPAR, Maria, Olivia, Christina.
"Impromptu speaking by lectures of english and indonesia".
Medan:
Universitas HKBP Nommensen,
2013.
Artikel.