Perhaps you should try some spelling variations:
hieu tieng » viet tieng, dien tieng, tiep tieng
dieu hien » dieu khien, dieu kien, bieu hien
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
nang xa » nang x, lang xa, nang ma
cac bac » cac bai, cac ban, cac cach
va hanh » van hanh, va thanh, va danh
vai cua » dai cua, hai cua, lai cua
bac va » ban va, bac ha, bao va
vi cua » di cua

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: tu sach ty nang xa hoi. ((hieu tieng) OR (dieu hien)) cac bac va hanh ((vi cua) OR (vai cua)) tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang xa hoi. ((hieu tieng) or (dieu hien)) cac bac va hanh ((vi cua) OR (vai cua)) tre~".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang xa hoi. ((hieu tieng) or (dieu hien)) cac bac va hanh ((vi cua) OR (vai cua)) tre*.