Perhaps you should try some spelling variations:
hieu cua » hieu qua, dieu cua, bieu cua
ban hanh » ban hang
cac tren » ca tren, cau tren, rac tren
lang xa » lang ha, dang xay, lang van
hop ban » hoc ban, hap ban, hon ban
hanh ve » hanh vi, hanh va, hanh kem
bac ky » cac ky, ban ky, sac ky
ve cac » va cac, vien cac

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: vu ((bach ky) or (bac ky)) lang xa hoi. hieu cua cac hop ban hanh ve cac tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu ((bach ky) OR (bac ky)) lang xa hoi. hieu cua cac hop ban hanh ve cac tren.
• Adding a wildcard symbol may retrieve word variants: vu ((bach ky) or (bac ky)) lang xa hoi. hieu cua cac hop ban hanh ve cac tren*.