Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
viet cua » viec cua, viet ca, biet cua
viet qua » vien quan, ket qua, viet ha
xang xa » lang xa, mang xa, ang xa
hieu ve » hieu va, hieu van
cac duc » cac du, cao duc, cac dac
va dinh » van dinh, va kinh, va tinh
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: ((toc sach) OR (doc sach)) ty xang xa hoi. hieu ve cac duc va dinh ((viet cua) OR (viet qua)) tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (doc sach)) ty xang xa hoi. hieu ve cac duc va dinh ((viet cua) or (viet qua)) tre~".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (doc sach)) ty xang xa hoi. hieu ve cac duc va dinh ((viet cua) or (viet qua)) tre*.