Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
hanh di » hanh vi, hanh de, hang di
thuc va » thuc dan, thuc day
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
nang xa » nang x, lang xa, nang ma
sai ky » sac ky
di cua » dai cua, doi cua, de cua
ve cam » ve cham, ve cac, va cam

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 thu) or (sai ky)) nang xa hoi. hieu ve cam ((thuc va) OR (thuc vat)) hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach thu) OR (sai ky)) nang xa hoi. hieu ve cam ((thuc va) OR (thuc vat)) hanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach thu) or (sai ky)) nang xa hoi. hieu ve cam ((thuc va) OR (thuc vat)) hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach thu) or (sai ky)) nang xa hoi. hieu ve cam ((thuc va) OR (thuc vat)) hanh di cua tre*.