Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
hanh thai » nhanh thai, hinh thai, anh thai
vien cac » vien bach, vien dai, vien da
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
hanh tai » thanh tai, hang tai, han tai
nuoc van » nuoc va, nuoc san, luoc van
sach ky » sac ky, sach ty, sach kem
nang co » nang cao, nang doc, nang noi
cua tre » cua te, cuu tre, cua triet
co hoi » co hoc, co loi

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 ky) OR (sach y)) nang co hoi. hieu vien cac nuoc van ((hanh thai) or (hanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach y)) nang co hoi. hieu vien cac nuoc van ((hanh thai) OR (hanh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) OR (sach y)) nang co hoi. hieu vien cac nuoc van ((hanh thai) or (hanh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) OR (sach y)) nang co hoi. hieu vien cac nuoc van ((hanh thai) or (hanh tai)) cua tre*.