Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu cua » hieu qua, dieu cua, bieu cua
nam thuc » nam thuoc, am thuc, nam thu
cau treo » cau theo, cau tren, cau triet
hieu ca » hieu cac, hieu va, hieu xa
tang xa » trang xa, tang ma, lang xa
sach ty » sach y, sach tu, sach thu
ty tang » tay tang, ty xang, ty hang
thuc va » thuc vat, thuc dan, thuc day
dan vai » dan va, dan tai, dan vat
cuu tre » cua tre, cau tren
va dan » ca dan, va dao, va dau

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 ty tang xa hoi. ((hieu ca) OR (hieu cua)) nam thuc va dan vai ((cuu tre) or (cau treo))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty tang xa hoi. ((hieu ca) OR (hieu cua)) nam thuc va dan vai ((cuu tre) OR (cau treo)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty tang xa hoi. ((hieu ca) OR (hieu cua)) nam thuc va dan vai ((cuu tre) or (cau treo))".
• Adding a wildcard symbol may retrieve word variants: toc sach ty tang xa hoi. ((hieu ca) OR (hieu cua)) nam thuc va dan vai ((cuu tre) or (cau treo))*.