Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
thuc dan » thuc hanh, hoc dan, thuc vat
cau treo » cau theo, cau tren, cau triet
hoc sach » hoc sinh, hoc cac, hoc anh
ky tang » ky nang, ky dang, kho tang
tang xa » trang xa, tang ma, lang xa
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc day
dan vai » dan va, dan tai, dan vat
vai cau » va cau, van cau, vai cac
va nam » van nam, ha nam, va nay

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