Perhaps you should try some spelling variations:
vai thiet » va thiet, tai thiet, van thiet
hieu cao » chieu cao, hieu cac, hieu ca
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cao hoi » cau hoi, co hoi, cao hoc
xuc van » luc van, vuc van, xuc ban
duc van » duc va, duc tan, duc manh
hanh va » hang va, hanh vi
va vai » va bai, va van, va dai

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 ky nang cao hoi. hieu cao chat ((xuc van) or (duc van)) hanh va vai thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang cao hoi. hieu cao chat ((xuc van) OR (duc van)) hanh va vai thiet.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang cao hoi. hieu cao chat ((xuc van) or (duc van)) hanh va vai thiet*.