Perhaps you should try some spelling variations:
cham duc » pham duc, cham soc, pham duy
van hanh » van thanh, ban hanh, van anh
hanh tai » thanh tai, hang tai, han tai
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va, hieu van
ve cham » va cham, ve chat, vu cham
duc van » duc va, duc tan, duc manh
su viet » so viet
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 duc van hanh tai su viet~.
• 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 duc van hanh tai su viet.
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang ma) or (nang x)) hoi. hieu ve cham duc van hanh tai su viet*.