Perhaps you should try some spelling variations:
mai khoi » mai khoa, tai khoa, cac khoi
nhan hoi » nhan hoa, nhan hoc, nhan hop
te sach » toc sach
hoi cua » hoi chuc
va nhan » van nhan, ca nhan, va phan
cau duc » cao duc, cau luc, chu duc
hieu va » lieu va
sach ky » sac ky, sach y, sach ty
dai hoi » dai hoc, dai hai, dai moi
cua tre » cua te, cuu tre, cua triet

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 ky nang ((mai khoi) or (dai hoi)). ((hieu va) OR (hieu qua)) cau duc va nhan hoi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky nang ((mai khoi) OR (dai hoi)). ((hieu va) OR (hieu qua)) cau duc va nhan hoi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky nang ((mai khoi) or (dai hoi)). ((hieu va) OR (hieu qua)) cau duc va nhan hoi cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ky nang ((mai khoi) or (dai hoi)). ((hieu va) OR (hieu qua)) cau duc va nhan hoi cua tre*.