Perhaps you should try some spelling variations:
hieu cua » hieu qua, dieu cua, bieu cua
vanh dai » van dai, vanh tai, lanh dao
cua nhan » ca nhan, cua ngan, cua nha
sach ky » sac ky, sach y, sach kem
sach ty » sach y, sach tu, sach thu
tuc va » thuc va, truc va, duc va
cua te » cua tu
x hoi » xa hoi, o hoi, x ho

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

• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach ty)) nang x hoi. hieu cua nhan ((tuc va) OR (tuc xa)) vanh dai cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) OR (sach ty)) nang x hoi. hieu cua nhan ((tuc va) or (tuc xa)) vanh dai cua te~".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) OR (sach ty)) nang x hoi. hieu cua nhan ((tuc va) or (tuc xa)) vanh dai cua te*.