Perhaps you should try some spelling variations:
ban hang » ngan hang
lang mai » lang dai, lang hai, lang man
cham hoc » cham soc, chat hoc, cham hoi
te sach » toc sach
sach ky » sac ky, sach y, sach ty
hang te » hang ke, hang tu, hang ve
hoc ban » hoc bang, hoc dan, hoc bai
va cham » va chat, va tham
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
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: te sach ky ((nang ma) or (lang mai)) hoi. hieu va cham hoc ban hang te ((cua te) OR (cua tu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky ((nang ma) OR (lang mai)) hoi. hieu va cham hoc ban hang te ((cua te) OR (cua tu)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky ((nang ma) or (lang mai)) hoi. hieu va cham hoc ban hang te ((cua te) OR (cua tu))".
• Adding a wildcard symbol may retrieve word variants: te sach ky ((nang ma) or (lang mai)) hoi. hieu va cham hoc ban hang te ((cua te) OR (cua tu))*.