Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
toc sach » hoc sach, doc sach, nuoc sach
ban hang » ngan hang
nang mai » nang ma, nang tai, lang mai
cam dua » ca dua, cay dua, chay dua
hai cuc » hai cua, thai cua, hai huoc
dua ban » dia ban, cua ban, qua ban
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ty nang » ky nang, ty xang, ty hang
ve cam » ve cham, ve cac, va cam

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) OR (thuoc sach)) ty nang mai hoi. hieu ve cam dua ban hang ((hai cuc) or (tai cuc)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (thuoc sach)) ty nang mai hoi. hieu ve cam dua ban hang ((hai cuc) OR (tai cuc)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (thuoc sach)) ty nang mai hoi. hieu ve cam dua ban hang ((hai cuc) or (tai cuc)) tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (thuoc sach)) ty nang mai hoi. hieu ve cam dua ban hang ((hai cuc) or (tai cuc)) tre*.