Government Service Insurance System (GSIS). (2011). GSIS art competition: 2011. [Government Service Insurance System].
Chicago-referens (17:e uppl.)Government Service Insurance System (GSIS). GSIS Art Competition: 2011. [Pasay City]: [Government Service Insurance System], 2011.
MLA-referens (9:e uppl.)Government Service Insurance System (GSIS). GSIS Art Competition: 2011. [Government Service Insurance System], 2011.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.