Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
va hanh » van hanh, va thanh, va danh
sach tu » sach thu, cach tu, sach ty
tu hanh » du hanh, lu hanh, thuc hanh
ve cac » va cac, vien cac
va cao » va cac, va co, va dao
vi cua » vai cua, di cua
cua te » cua tu
o hai » co hai, so hai, o lai
o hoi » co hoi, o hoc, o 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 tu hanh ((o hoi) or (o hai)). hieu ((ve cac) or (va cao)) duc va hanh vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach tu hanh ((o hoi) OR (o hai)). hieu ((ve cac) OR (va cao)) duc va hanh vi cua te.
• Adding a wildcard symbol may retrieve word variants: tu sach tu hanh ((o hoi) or (o hai)). hieu ((ve cac) or (va cao)) duc va hanh vi cua te*.