Perhaps you should try some spelling variations:
dang xay » dang van
van hanh » van thanh, ban hanh, van anh
hanh tai » thanh tai, hang tai, han tai
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
cao luc » bao luc, cao duc, cao suc
luc van » luoc van, luu van, duc van
va cao » va cac, va co, va dao
cua tu » cua tuc, cua su, cua cu

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky ((dang xay) or (van xay)) hoi. lieu va cao luc van hanh tai ((cua te) OR (cua tu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((dang xay) OR (van xay)) hoi. lieu va cao luc van hanh tai ((cua te) OR (cua tu))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((dang xay) or (van xay)) hoi. lieu va cao luc van hanh tai ((cua te) OR (cua tu))*".