Perhaps you should try some spelling variations:
hieu hien » bieu hien, dieu hien, chieu chien
hieu vien » hieu viec, thieu nien, hieu tieng
thu sach » tu sach, thuat sach, thuoc sach
sach ky » sac ky, sach y, sach ty
cac tac » cac toc, cac bac, cac dac
va hanh » van hanh, va thanh, va danh
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: thu sach ky nang x ho. ((hieu vien) or (hieu hien)) cac tac va hanh vi ((cua te) OR (cua tu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang x ho. ((hieu vien) OR (hieu hien)) cac tac va hanh vi ((cua te) OR (cua tu)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang x ho. ((hieu vien) or (hieu hien)) cac tac va hanh vi ((cua te) OR (cua tu))".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang x ho. ((hieu vien) or (hieu hien)) cac tac va hanh vi ((cua te) OR (cua tu))*.