Perhaps you should try some spelling variations:
hieu hien » bieu hien, dieu hien, chieu chien
hieu vien » hieu viec, thieu nien, hieu tieng
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
va hanh » van hanh, va thanh, va danh
cuu tre » cua tre, cau tren, cau treo
nang o » nang co, nang ho, nang ro
cac tu » cac thu, cach tu, cac du
vi cuu » vi luu, vinh cuu
o hoi » co hoi, o hoc, o hai

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 o hoi. ((hieu vien) or (((hieu hien) or (dieu khien)))) cac tu va hanh vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang o hoi. ((hieu vien) OR (((hieu hien) OR (dieu khien)))) cac tu va hanh vi cuu tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang o hoi. ((hieu vien) or (((hieu hien) or (dieu khien)))) cac tu va hanh vi cuu tre*.