Perhaps you should try some spelling variations:
doc sach » toc sach, nuoc sach, dac sac
hoc sach » hoc sinh, hoc cac, hoc anh
lang van » dang van, tang van, hoang van
thuc day » thuc dan
tai cuu » tai cuc, tai buu, tai cua
dan tai » van tai, dan thi, han tai
hieu va » lieu va, hieu qua
van hoe » van hoa, van hoc, van hieu
ky lang » ky nang, ky dang, ky tang
cuu tre » cua tre, cau tren, cau treo
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: ((doc sach) OR (hoc sach)) ky lang van hoe. hieu va nam ((thuc vat) or (thuc day)) dan tai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc sach) OR (hoc sach)) ky lang van hoe. hieu va nam ((thuc vat) OR (thuc day)) dan tai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doc sach) OR (hoc sach)) ky lang van hoe. hieu va nam ((thuc vat) or (thuc day)) dan tai cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((doc sach) OR (hoc sach)) ky lang van hoe. hieu va nam ((thuc vat) or (thuc day)) dan tai cuu tre*.