Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
va trien » va truyen, va thiet, va tuyen
va triet » va thiet, ve triet, cua triet
hanh vai » hanh vi, hanh va, hanh tai
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
cac toc » cac toi, cac nuoc, cac thoi
sach ky » sac ky, sach y, sach ty
cac tuc » cac tu, cac tac, cac nuoc
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh

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 dang xa hoi. hieu vien ((cac tuc) or (cac toc)) van hanh vai ((va triet) OR (va trien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky dang xa hoi. hieu vien ((cac tuc) OR (cac toc)) van hanh vai ((va triet) OR (va trien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky dang xa hoi. hieu vien ((cac tuc) or (cac toc)) van hanh vai ((va triet) OR (va trien))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky dang xa hoi. hieu vien ((cac tuc) or (cac toc)) van hanh vai ((va triet) OR (va trien))*.