Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, nam thu, nam tu
dan vat » dang vat, van vat, dan va
dan tai » van tai, dan thi, han tai
cuu tre » cua tre, cau tren, cau treo
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh

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