Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
dan vat » dang vat, van vat, dan dat
dan vai » dan tai, den vai, dang van
sach ky » sac ky, sach y, sach ty
thuc ca » thuc cua, thuc can, thuc cao
cuu tre » cua tre, cau tren, cau treo
hieu va » lieu va, hieu qua
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh
va nam » van nam, ha nam, va nay
dan va » doan va, dan ca, ban va

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 ca ((dan vai) or (((dan vat) OR (dan va)))) 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 ca ((dan vai) OR (((dan vat) OR (dan va)))) 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 ca ((dan vai) or (((dan vat) OR (dan va)))) cuu tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky dang xa hoi. hieu va nam thuc ca ((dan vai) or (((dan vat) OR (dan va)))) cuu tre*.