Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hang vai » hang va, hang tai, hang hai
hieu van » hieu va, thien van, lieu va
cau tren » cu tren, dau tren, ca tren
sach ty » sach y, sach tu, sach thu
van cau » van dau, van hau, van chat
dua ban » dia ban, qua ban, mua ban
ty nang » ky nang, ty xang, ty hang
vai cau » va cau, vai cac, lai chau
ma hoi » mai hoi, xa hoi, me hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ty nang ((ma hoi) or (ma hoa)). hieu van cau ((dua ban) OR (cua ban)) hang vai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty nang ((ma hoi) OR (ma hoa)). hieu van cau ((dua ban) OR (cua ban)) hang vai cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ty nang ((ma hoi) or (ma hoa)). hieu van cau ((dua ban) OR (cua ban)) hang vai cau tren".
• Adding a wildcard symbol may retrieve word variants: thu sach ty nang ((ma hoi) or (ma hoa)). hieu van cau ((dua ban) OR (cua ban)) hang vai cau tren*.