Perhaps you should try some spelling variations:
nghien thu » nghiem thuc, nghiep thuc, nghien cuu
cong hop » tong hop, cong hoa, cong ho
hop toan » hop hoan, phap toan, tap toan
khoa hoc » hoa hoc
tuan van » luan van, tran van, tan van
so sach » so sanh, bo sach, co sach
hoi tap » hoi dap, hoc tap, hai tap
hoi tai » hoc tai, hoi trac
hoi anh » hoi danh, hoc anh, hai anh
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ((hoi tap) or (hoi tai)), nghien thu cong hop toan khoa hoc ma hoi anh tuan van~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((hoi tap) OR (hoi tai)), nghien thu cong hop toan khoa hoc ma hoi anh tuan van.
• Adding a wildcard symbol may retrieve word variants: so sach ((hoi tap) or (hoi tai)), nghien thu cong hop toan khoa hoc ma hoi anh tuan van*.