Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
nang mai » nang ma, nang tai, lang mai
cua viet » ca viet, hoa viet, cua vat
mai hoi » mai khoi, dai hoi, lai hoi
sach ty » sach tu, sach thu, xach tay
cac xuc » cac nuoc, chat xuc, cac cuoc
va hanh » van hanh, va thanh, va danh
vi cua » vai cua, di cua

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 ty) OR (sach y)) nang mai hoi. hieu vien ((cac xuc) or (cam xuc)) va hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach y)) nang mai hoi. hieu vien ((cac xuc) OR (cam xuc)) va hanh vi cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) OR (sach y)) nang mai hoi. hieu vien ((cac xuc) or (cam xuc)) va hanh vi cua viet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) OR (sach y)) nang mai hoi. hieu vien ((cac xuc) or (cam xuc)) va hanh vi cua viet*.