Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
dieu hien » dieu khien, dieu kien, bieu hien
cau tren » cu tren, dau tren, ca tren
cuu tre » cua tre, cau treo
danh vi » hanh vi, dinh vi, danh di
va danh » va dinh, va dan, va hanh
tu sach » thu sach, su sach, te sach
cac bac » cac bai, cac ban, cac cach
sach ky » sac ky, sach y, sach ty
bac va » ban va, bac ha, bao va
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: tu sach ky nang x hoi. ((hieu vien) or (dieu hien)) cac bac va danh vi ((cuu tre) OR (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. ((hieu vien) OR (dieu hien)) cac bac va danh vi ((cuu tre) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. ((hieu vien) or (dieu hien)) cac bac va danh vi ((cuu tre) OR (cau tren))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. ((hieu vien) or (dieu hien)) cac bac va danh vi ((cuu tre) OR (cau tren))*.