Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, nang ma
lang ha » long ha
hieu vu » hieu va, hieu ve, hieu su
vu cham » va cham, vu kham, tu cham
cham tu » pham tu, cam tu, chai tu
tu van » tu va
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 vu cham tu van 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 vu cham tu van hanh vi cau tren.
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang xa) or (lang ha)) hoi. hieu vu cham tu van hanh vi cau tren*.