Perhaps you should try some spelling variations:
nghien thu » nghiem thuc, nghiep thuc, nghien cuu
manh tong » manh tuong, manh tung, manh long
sach hoc » cach hoc, sach hoi, mach hoc
cong hoc » dong hoc, cong hoa, cong ho
cong coc » cong cuoc, cong cac, cong co
cac nhan » ca nhan, cac nha, cam nhan
nhan dan » phan dau, gian dan, nhan tai
tu sach » thu sach, su sach, te sach
hoi cac » hoc cac, voi cac, hoa cac
hop ma » hop may, hoc ma, hop va
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: tu sach hoc tap, nghien thu ((cong hoc) or (cong coc)) manh tong hop ma hoi cac nhan dan~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoc tap, nghien thu ((cong hoc) OR (cong coc)) manh tong hop ma hoi cac nhan dan.
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien thu ((cong hoc) or (cong coc)) manh tong hop ma hoi cac nhan dan*.