Perhaps you should try some spelling variations:
ban hang » ngan hang
cham duc » pham duc, cham soc, pham duy
tu sach » thu sach, su sach, te sach
tieu su » thieu so
sach ky » sac ky, sach y, sach ty
hieu vu » hieu va, hieu ve, hieu su
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
may va » may vi, day va
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: tu sach ky nang ma hoi. ((hieu vu) or (tieu su)) cham duc ((ban hanh) or (ban hang)) may va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ma hoi. ((hieu vu) OR (tieu su)) cham duc ((ban hanh) OR (ban hang)) may va thiet.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ma hoi. ((hieu vu) or (tieu su)) cham duc ((ban hanh) or (ban hang)) may va thiet*.