Perhaps you should try some spelling variations:
van thiet » va thiet, dan thiet, can thiet
vu sach » vu bach, su sach, vu khach
sach ty » sach y, sach tu, sach thu
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
hieu ve » hieu va, hieu van
ve chao » ve chat, ve cham, ve cho
va hanh » van hanh, va thanh, va danh
hanh va » hang va, hanh vi
xu va » xu van, tu va, su va

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ty ((nang xa) or (lang xa)) hoi. hieu ve chao xu va hanh va van thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ty ((nang xa) OR (lang xa)) hoi. hieu ve chao xu va hanh va van thiet.
• Adding a wildcard symbol may retrieve word variants: vu sach ty ((nang xa) or (lang xa)) hoi. hieu ve chao xu va hanh va van thiet*.