Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
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
thuc ca » thuc cua, thuc can, thuc cao
dan vai » dan tai, dan vat, den vai
dan va » doan va, dan ca, ban va
qua am » quan am, qua ap, cua am

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 qua am thuc ca ((dan vai) or (dan va)) 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 qua am thuc ca ((dan vai) OR (dan va)) 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 qua am thuc ca ((dan vai) or (dan va)) cau treo".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (doc sach)) ky tang xa hoi. hieu qua am thuc ca ((dan vai) or (dan va)) cau treo*.