Perhaps you should try some spelling variations:
nghien cam » nghiep cam, nghien cuu, nghiep cay
doanh khoa » toan khoa
thanh nhan » thanh phan, thanh san, thanh toan
cac doanh » cac dan, cac dang, van doanh
sach hoc » cach hoc, sach hoi, mach hoc
nang cac » nang cao, bang cac, hang cac
khoa hoc » hoa hoc
tu sach » thu sach, su sach, te sach
hai van » thai van, ha van, hai tan
hoc xa » hoc ma
xa hai » xa thai, xua hai, xa hoi
toan » tran

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach hoc tap, nghien cam nang cac doanh khoa hoc xa hai van ((thanh nhan) or (tinh toan))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoc tap, nghien cam nang cac doanh khoa hoc xa hai van ((thanh nhan) OR (tinh toan)).
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cam nang cac doanh khoa hoc xa hai van ((thanh nhan) or (tinh toan))*.