Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
cau treo » cau theo, cau tren, cau triet
ky dang » ky danh
hieu va » lieu va
thuc va » thuc vat, thuc dan, thuc day
dan thi » dang thi, tran thi, dinh thi
thi cau » thi chau, thi cu, thi cam
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 ((ky dang) or (ky nang)) xa hoi. ((hieu va) OR (hieu qua)) nam thuc va dan thi cau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ky dang) OR (ky nang)) xa hoi. ((hieu va) OR (hieu qua)) nam thuc va dan thi cau treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ky dang) or (ky nang)) xa hoi. ((hieu va) OR (hieu qua)) nam thuc va dan thi cau treo".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ky dang) or (ky nang)) xa hoi. ((hieu va) OR (hieu qua)) nam thuc va dan thi cau treo*.