Perhaps you should try some spelling variations:
thien van » thi van
thai cua » tai cuc, tri cua, dai cua
than cua » nhan cua, ban cua, gian cua
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
du van » duy van, duc van, tu van
nang o » nang co, nang ho, nang ro
o hai » co hai, so hai, o lai

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 o hai. ((hieu ve) or (thien van)) cac du van hanh ((than cua) OR (thai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang o hai. ((hieu ve) OR (thien van)) cac du van hanh ((than cua) OR (thai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang o hai. ((hieu ve) or (thien van)) cac du van hanh ((than cua) OR (thai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang o hai. ((hieu ve) or (thien van)) cac du van hanh ((than cua) OR (thai cua)) tre*.