Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
hanh tai » thanh tai, hang tai, han tai
hanh vai » hanh vi, hanh va, hanh van
te sach » toc sach
ky dang » ky nang, ky danh
dang xa » dang xay, lang xa, dang ha
cac tac » cac toc, cac bac, cac dac
sach ky » sac ky, sach y, sach ty
thiet » thieu

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky dang xa hoi. hieu vien ((cac tac) or (dat nuoc)) van ((hanh vai) OR (hanh tai)) va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky dang xa hoi. hieu vien ((cac tac) OR (dat nuoc)) van ((hanh vai) OR (hanh tai)) va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky dang xa hoi. hieu vien ((cac tac) or (dat nuoc)) van ((hanh vai) OR (hanh tai)) va thiet".
• Adding a wildcard symbol may retrieve word variants: te sach ky dang xa hoi. hieu vien ((cac tac) or (dat nuoc)) van ((hanh vai) OR (hanh tai)) va thiet*.