Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
ban hanh » ban hang
van hanh » van thanh, van anh, van ban
chat tu » nhat tu, chai tu, chay tu
va chat » van chat, va phat, cao chat
tu sach » thu sach, su sach, te sach
lang ha » long ha
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
vi cau » va cau, ve cau, di cau

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 y ((nang xa) or (lang ha)) hoi. hieu va chat tu ((van hanh) or (ban hanh)) vi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((nang xa) OR (lang ha)) hoi. hieu va chat tu ((van hanh) OR (ban hanh)) vi cau tren.
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang xa) or (lang ha)) hoi. hieu va chat tu ((van hanh) or (ban hanh)) vi cau tren*.