Perhaps you should try some spelling variations:
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
ve chat » va chat, van chat
duc van » duc va, duc tan, duc manh
su tien » su kien, su hien, tu tieng
ve cham » va cham, vu cham, ve chim
nang ma » tang ma, sang ma, nang cao
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 ma) or (nang x)) hoi. hieu ((ve cham) OR (ve chat)) duc van hanh tai su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((nang ma) OR (nang x)) hoi. hieu ((ve cham) OR (ve chat)) duc van hanh tai su tien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((nang ma) or (nang x)) hoi. hieu ((ve cham) OR (ve chat)) duc van hanh tai su tien".
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang ma) or (nang x)) hoi. hieu ((ve cham) OR (ve chat)) duc van hanh tai su tien*.