Perhaps you should try some spelling variations:
van thieu » van hieu, van tieu, van thien
mai khoi » mai khoa, tai khoa, cac khoi
va chat » van chat, va phat, cao chat
sach ty » sach y, sach tu, sach thu
tu sach » thu sach, su sach, te sach
mai hoi » dai hoi, lai hoi, mai doi
ty nang » ky nang, ty xang, ty hang
hieu va » lieu va, hieu qua
xac va » tac va, ac va, bac va
luc va » duc va, tuc va, loc va

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 ty nang ((mai hoi) OR (mai khoi)). hieu va chat ((xac va) or (luc va)) hanh vi van thieu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang ((mai hoi) OR (mai khoi)). hieu va chat ((xac va) OR (luc va)) hanh vi van thieu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang ((mai hoi) OR (mai khoi)). hieu va chat ((xac va) or (luc va)) hanh vi van thieu".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang ((mai hoi) OR (mai khoi)). hieu va chat ((xac va) or (luc va)) hanh vi van thieu*.