Gaya APA

Bopp, , R, ., Smith, , L, C, . (2001). Reference and Information Services (3th edition). : Libraries Unlimeted.Englewood.

Gaya MLA

Bopp, , Richard, ., Smith, , Linda, C, . "Reference and Information Services". 3th edition : Libraries Unlimeted.Englewood, 2001. Koleksi Elektronik.