Perhaps you should try some spelling variations:
dieu kien » dieu khien, dien bien
hieu vien » hieu hien, hieu viec, thieu nien
tu sach » thu sach, su sach, te sach
cac tac » cac toc, cac bac, cac dac
va hang » van hang, va nang, va lang
hang di » hang doi, hang vi, hang dien
y nang » ky nang, ly nang, v nang
tac va » tac da, tac xa, tuc va
cua tu » cua tuc, cua su, cua cu

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 x ho. ((hieu vien) or (dieu kien)) cac tac va hang di ((cua te) or (cua tu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang x ho. ((hieu vien) OR (dieu kien)) cac tac va hang di ((cua te) OR (cua tu)).
• Adding a wildcard symbol may retrieve word variants: tu sach y nang x ho. ((hieu vien) or (dieu kien)) cac tac va hang di ((cua te) or (cua tu))*.