Perhaps you should try some spelling variations:
dung doi » huong doi, dung tai, dung co
doi cua » dai cua, hoi cua
sach ty » sach tu, sach thu, xach tay
cua tre » cua te, cuu tre, cua triet
qua cam » qua cham, qua cac, qua ca
tu vat » tu va, tu van, tu dat
tu bat » tu ban, tu dat
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ty) or (sach y)) nang x hoi. hieu qua cam ((tu vat) OR (tu bat)) dung doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach y)) nang x hoi. hieu qua cam ((tu vat) OR (tu bat)) dung doi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) or (sach y)) nang x hoi. hieu qua cam ((tu vat) OR (tu bat)) dung doi cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) or (sach y)) nang x hoi. hieu qua cam ((tu vat) OR (tu bat)) dung doi cua tre*.