Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
van hanh » van thanh, ban hanh, van anh
cac xuc » cam xuc, cac nuoc, chat xuc
lai cua » dai cua, hai cua, lai chau
va hanh » va thanh, va danh, ban hanh
sach ky » sac ky, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet

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