Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
thuc va » thuc vat, thuc dan, thuc day
sach ty » sach y, sach tu, xach tay
cua tre » cua te, cuu tre, cua triet
nang xa » nang x, lang xa, nang ma
va cao » va cac, va co, va dao
va dau » va dao
dau di » da di, dau da, dau do
di cua » dai cua, doi cua, de cua
va cam » va cham, va cac, va cai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach ty) OR (sach thu)) nang xa hoi. hieu ((va cam) or (va cao)) thuc va dau di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach thu)) nang xa hoi. hieu ((va cam) OR (va cao)) thuc va dau di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) OR (sach thu)) nang xa hoi. hieu ((va cam) or (va cao)) thuc va dau di cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) OR (sach thu)) nang xa hoi. hieu ((va cam) or (va cao)) thuc va dau di cua tre*.