Perhaps you should try some spelling variations:
thien van » thi van
hieu van » hieu va, lieu va, hieu ve
thanh va » thanh van, hanh va, thanh ha
cau tren » cu tren, dau tren, ca tren
sach tu » sach thu, cach tu, sach ty
nang ma » tang ma, sang ma, nang cao
soc gia » hoc gia, so gia, quoc gia
toc gia » toc giay, tac gia, quoc gia
tu nang » tru nang, tu nong, tu nano
so sach » so sanh, bo sach, co sach
ma hoi » mai hoi, xa hoi, ma hoa
va cau » van cau, va cac, va dau

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach tu nang ma hoi. ((hieu van) OR (thien van)) cham ((soc gia) or (toc gia)) thanh va cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach tu nang ma hoi. ((hieu van) OR (thien van)) cham ((soc gia) OR (toc gia)) thanh va cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach tu nang ma hoi. ((hieu van) OR (thien van)) cham ((soc gia) or (toc gia)) thanh va cau tren".
• Adding a wildcard symbol may retrieve word variants: so sach tu nang ma hoi. ((hieu van) OR (thien van)) cham ((soc gia) or (toc gia)) thanh va cau tren*.