Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
toc sach » hoc sach, doc sach, thuoc sach
cam tuc » cam xuc, cam tu, nam thuc
ca tren » cau tren, cu tren, la tren
hieu va » lieu va, hieu qua
y nang » ky nang, ly nang, v nang
ma hoi » mai hoi, ma hoa, me hoi
hai ca » hai cua, hai ba, bai ca
va cam » va cham, va cac, va cao

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 y nang ((ma hoi) OR (xa hoi)). hieu va cam tuc ((ban thanh) or (gia thanh)) hai ca tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y nang ((ma hoi) OR (xa hoi)). hieu va cam tuc ((ban thanh) OR (gia thanh)) hai ca tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y nang ((ma hoi) OR (xa hoi)). hieu va cam tuc ((ban thanh) or (gia thanh)) hai ca tren".
• Adding a wildcard symbol may retrieve word variants: toc sach y nang ((ma hoi) OR (xa hoi)). hieu va cam tuc ((ban thanh) or (gia thanh)) hai ca tren*.