Perhaps you should try some spelling variations:
mai khoi » mai khoa, tai khoa, dai khoa
hang tai » hang va
cac khoi » cac thoi, cac khoan, cach thoi
duc manh » suc manh, duc anh, duc minh
tu sach » thu sach, su sach, te sach
dao duc » giao duc, tao duoc
hieu ve » hieu va, hieu van
cuu tre » cua tre, cau tren, cau treo
ve dao » de dao, va dao, ve bao
sach o » sach lo, sac o, sach y
o lang » hoa lang, hoi lang

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 o lang ((mai khoi) or (cac khoi)). hieu ve dao duc manh ((hang tai) OR (dung tai)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach o lang ((mai khoi) OR (cac khoi)). hieu ve dao duc manh ((hang tai) OR (dung tai)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach o lang ((mai khoi) or (cac khoi)). hieu ve dao duc manh ((hang tai) OR (dung tai)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach o lang ((mai khoi) or (cac khoi)). hieu ve dao duc manh ((hang tai) OR (dung tai)) cuu tre*.