Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
cua viet » ca viet, hoa viet, cua vat
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
mai hoi » mai khoi, dai hoi, lai hoi
vien da » vien dai, hien dai
va hanh » van hanh, va thanh, va danh
ma hoi » xa hoi, ma hoa, me hoi
xuc va » duc va, tuc va, luc va
vi cua » vai cua, di cua

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty nang ((ma hoi) OR (mai hoi)). hieu vien da xuc va hanh vi cua viet~".
• Adding a wildcard symbol may retrieve word variants: su sach ty nang ((ma hoi) OR (mai hoi)). hieu vien da xuc va hanh vi cua viet*.