Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
tinh cua » trinh cua, sinh cua, tinh chat
van hanh » van thanh, ban hanh, van anh
van tuan » van quan, van ban, anh tuan
cac xuc » cam xuc, cac nuoc, chat xuc
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
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 ((nang xa) or (nang ma)) hoi. hieu vien cac xuc ((van tuan) or (van hanh)) tinh cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (nang ma)) hoi. hieu vien cac xuc ((van tuan) OR (van hanh)) tinh cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) or (nang ma)) hoi. hieu vien cac xuc ((van tuan) or (van hanh)) tinh cua tre*.