Perhaps you should try some spelling variations:
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
dang xay » dang van, van xay
tu sach » thu sach, su sach, te sach
loc van » luoc van, hoc van, lo van
cac loc » cac lop, cac toc, cac hoc
hieu va » lieu va, hieu qua
su viet » so viet
nang xa » nang x, lang xa, nang ma
lang ha » long ha
tai su » tai so, tai tu, lai su

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 (dang xay))) or (lang ha)) hoi. hieu va cac loc van hanh tai su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((((nang xa) OR (dang xay))) OR (lang ha)) hoi. hieu va cac loc van hanh tai su viet.
• Adding a wildcard symbol may retrieve word variants: tu sach y ((((nang xa) or (dang xay))) or (lang ha)) hoi. hieu va cac loc van hanh tai su viet*.