Perhaps you should try some spelling variations:
nhanh hai » nhanh thai, thanh hai, nhanh ha
hanh hai » thanh hai, hang hai, hanh tai
sach ky » sac ky, sach y, sach kem
cac luc » cau luc, coc luc, cac nuoc
qua cac » cua cac
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
luc va » duc va, tuc va, loc va
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 ky) OR (sach ty)) nang x hoi. hieu qua cac luc va ((hanh hai) or (nhanh hai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach ty)) nang x hoi. hieu qua cac luc va ((hanh hai) OR (nhanh hai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) OR (sach ty)) nang x hoi. hieu qua cac luc va ((hanh hai) or (nhanh hai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) OR (sach ty)) nang x hoi. hieu qua cac luc va ((hanh hai) or (nhanh hai)) cua tre*.