Perhaps you should try some spelling variations:
hanh cua » manh cua, hang cua, hanh sua
van hanh » van thanh, ban hanh, van anh
so sach » so sanh, bo sach, co sach
lang xa » lang ha, dang xay, lang van
nang ma » tang ma, sang ma, nang cao
luc van » luoc van, luu van, duc van
va cam » va cham, va cac, va cao
ve cam » ve cham, ve cac, ve cai
cua va » cua vat, chua va, cua van
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach y ((lang xa) or (nang ma)) hoi. hieu ((ve cam) OR (va cam)) luc van hanh cua va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y ((lang xa) OR (nang ma)) hoi. hieu ((ve cam) OR (va cam)) luc van hanh cua va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach y ((lang xa) or (nang ma)) hoi. hieu ((ve cam) OR (va cam)) luc van hanh cua va thiet".
• Adding a wildcard symbol may retrieve word variants: so sach y ((lang xa) or (nang ma)) hoi. hieu ((ve cam) OR (va cam)) luc van hanh cua va thiet*.