Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
thuc dan » thuc hanh, hoc dan, thuc vat
nam thuc » nam thuoc, am thuc, nam thu
cau treo » cau theo, cau tren, cau triet
doc sach » hoc sach, nuoc sach, dac sac
ky tang » ky nang, ky dang, kho tang
tang xa » trang xa, tang ma, lang xa
hieu ca » hieu cac, hieu cua, hieu va
dan dan » dang dan, ban dan, dao dan
dan vai » dan va, dan tai, dan vat
cuu tre » cua tre, cau tren
ca nam » cua nam, cai nam, ha nam

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