Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
thanh va » thanh van, hanh va, thanh ha
dau tren » dau tien, dat tren, dau tieng
hoc sach » hoc sinh, hoc cac, hoc anh
xang ha » lang ha, tang ha, dang ha
hieu va » lieu va, hieu qua
cao luc » bao luc, cao duc, cao suc
luc gia » luoc gia, duc gia, quoc gia
ha hoi » hoa hoi, ha noi, xa hoi
va cao » va cac, va co, va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) OR (hoc sach)) ty xang ha hoi. hieu va cao luc gia ((hanh vi) or (thanh va)) dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) ty xang ha hoi. hieu va cao luc gia ((hanh vi) OR (thanh va)) dau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (hoc sach)) ty xang ha hoi. hieu va cao luc gia ((hanh vi) or (thanh va)) dau tren".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (hoc sach)) ty xang ha hoi. hieu va cao luc gia ((hanh vi) or (thanh va)) dau tren*.