Perhaps you should try some spelling variations:
sach hoc » cach hoc, sach hoi, mach hoc
cuu cong » cua cong, thu cong, cac cong
cong coc » cong cuoc, cong cac, cong co
coc toan » ngoc toan, coc khoan, quoc toan
khoa hoc » hoa hoc
nhan van » nhan dan, nhan va, phan van
te sach » toc sach
hoc dai » hoc dan
hoi van » hoi va, hoi dan, hoi han
hai van » thai van, ha van, hai tan

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach hoc tap, nghien cuu cong coc toan khoa hoc dai ((hoi van) or (hai van)) nhan van~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach hoc tap, nghien cuu cong coc toan khoa hoc dai ((hoi van) OR (hai van)) nhan van.
• Adding a wildcard symbol may retrieve word variants: te sach hoc tap, nghien cuu cong coc toan khoa hoc dai ((hoi van) or (hai van)) nhan van*.