Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu van
hieu va » lieu va, hieu qua
duc van » duc tan, duc manh, duc phan
anh ve » hanh ve, anh va, anh viet
ve cau » ke cau, va cau, ve cac

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 x ho. ((hieu ve) or (hieu va)) cham ((duc van) OR (duc va)) anh ve cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x ho. ((hieu ve) OR (hieu va)) cham ((duc van) OR (duc va)) anh ve cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x ho. ((hieu ve) or (hieu va)) cham ((duc van) OR (duc va)) anh ve cau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x ho. ((hieu ve) or (hieu va)) cham ((duc van) OR (duc va)) anh ve cau tren*.