Perhaps you should try some spelling variations:
hieu hien » bieu hien, dieu hien, chieu chien
hieu vien » hieu viec, thieu nien, hieu tieng
cua viet » ca viet, hoa viet, cua vat
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
sach ty » sach y, sach tu, sach thu
truc va » thuc va, thuc vat, trung va
su sach » so sach, vu sach
ma hoi » mai hoi, xa hoi, ma hoa
tuc va » thuc va, tuc xa, duc va
vi cua » vai cua, di cua

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

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