Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien dai » hien dai
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
tu can » tu ban, tu cac, thu canh
dan vi » doan vi, don vi, dan va
vi cua » vai cua, di cua
tu ca » tu cac, tu cua, tu cay

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 y nang xa hoi. hieu vien dai ((tu ca) OR (tu can)) dan vi cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang xa hoi. hieu vien dai ((tu ca) OR (tu can)) dan vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang xa hoi. hieu vien dai ((tu ca) OR (tu can)) dan vi cua tre*.