Perhaps you should try some spelling variations:
viet cua » viec cua, viet ca, viet qua
toc sach » hoc sach, doc sach, thuoc sach
cac duc » cac du, cao duc, cac dac
va tinh » may tinh
va dinh » van dinh, va kinh, vu dinh
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
xang ma » tang ma, nang ma, sang ma
ma hoi » mai hoi, xa hoi, ma hoa
ve cac » va cac, vien cac

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: ((te sach) OR (toc sach)) ty xang ma hoi. hieu ve cac duc ((va dinh) OR (va tinh)) viet cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ty xang ma hoi. hieu ve cac duc ((va dinh) or (va tinh)) viet cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ty xang ma hoi. hieu ve cac duc ((va dinh) or (va tinh)) viet cua tre*.