Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
hac truc » hoc truc, hang truc, sach truc
su sach » so sach, vu sach
co sach » bo sach, cuon sach, hoc sach
hieu va » lieu va, hieu qua
truc va » thuc va, thuc vat, trung va
va hanh » van hanh, va thanh, va danh
v nang » va nang, vu nang, van nang
va hac » van hac, va khac, va cac
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: ((su sach) or (co sach)) v nang x ho. hieu va hac truc va hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (co sach)) v nang x ho. hieu va hac truc va hanh vi cua viet.
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (co sach)) v nang x ho. hieu va hac truc va hanh vi cua viet*.