Perhaps you should try some spelling variations:
hieu hien » bieu hien, dieu hien, chieu chien
hieu vien » hieu viec, thieu nien, hieu tieng
sach ky » sac ky, sach y, sach ty
cac bac » cac bai, cac ban, cac cach
su sach » so sach, vu sach
bac va » ban va, bac ha, bao va
va don » va dong, va doc, va do
vi cau » va cau, ve cau, viet cau
di cau » da cau, diem cau
x hoi » xa hoi, o hoi, x ho

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky nang x hoi. ((hieu vien) or (hieu hien)) cac bac va don ((vi cau) OR (di cau)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang x hoi. ((hieu vien) OR (hieu hien)) cac bac va don ((vi cau) OR (di cau)) tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang x hoi. ((hieu vien) or (hieu hien)) cac bac va don ((vi cau) OR (di cau)) tren".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang x hoi. ((hieu vien) or (hieu hien)) cac bac va don ((vi cau) OR (di cau)) tren*.