(1999). Higher Education General Information Survey (HEGIS), 1980-1981 Earned Degrees / United States Department of Education. National Center for Education Statistics. [electronic resource].
Чикаго-гийн эшлэл (17 дахь хэвлэлт)Higher Education General Information Survey (HEGIS), 1980-1981 Earned Degrees / United States Department of Education. National Center for Education Statistics. [electronic Resource]. 1999.
MLA -ийн эшлэл (9 дэх хэвлэлт)Higher Education General Information Survey (HEGIS), 1980-1981 Earned Degrees / United States Department of Education. National Center for Education Statistics. [electronic Resource]. 1999.
Анхааруулга: Эдгээр ишлэлүүд үргэлж 100% үнэн зөв биш байж магадгүй.