Perhaps you should try some spelling variations:
doanh khoa » toan khoa
thanh van » thanh san, thanh toan, thanh phan
thu sach » tu sach, thuat sach, thuoc sach
sach hoc » cach hoc, sach hoi, mach hoc
cuu long » cuu cong, cuu tong, cuu nang
so doanh » so danh, su doanh, hoa doanh
khoa hoc » hoa hoc
thai van » thi van, thai vung, thai son
long so » long soc, cong so, dong so
hoc xa » hoc ma

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach hoc tap, nghien cuu long so doanh khoa hoc xa ((thai van) OR (thai den)) thanh van~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach hoc tap, nghien cuu long so doanh khoa hoc xa ((thai van) OR (thai den)) thanh van".
• Adding a wildcard symbol may retrieve word variants: thu sach hoc tap, nghien cuu long so doanh khoa hoc xa ((thai van) OR (thai den)) thanh van*.