Perhaps you should try some spelling variations:
hieu hien » bieu hien, dieu hien, chieu chien
van hanh » van thanh, ban hanh, van anh
cap nuoc » dat nuoc
cua viet » ca viet, hoa viet, cua vat
nang tai » hang tai, tang tai, sang tai
nang mai » nang ma, lang mai, nang cai
sach ty » sach y, sach tu, sach thu
tu sach » thu sach, su sach, te sach
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 ((nang mai) OR (nang tai)) hoi. hieu hien ((cap nuoc) or (cam xuc)) van hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang mai) OR (nang tai)) hoi. hieu hien ((cap nuoc) OR (cam xuc)) van hanh vi cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((nang mai) OR (nang tai)) hoi. hieu hien ((cap nuoc) or (cam xuc)) van hanh vi cua viet".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang mai) OR (nang tai)) hoi. hieu hien ((cap nuoc) or (cam xuc)) van hanh vi cua viet*.