Perhaps you should try some spelling variations:
va trien » va truyen, va thiet, va tuyen
hieu van » hieu va, thien van, lieu va
va triet » va thiet, ve triet, cua triet
danh dau » lanh dao, hang dau, danh tu
van cham » van chat, van tham, va cham
cham loc » cham soc, chon loc, cham o
va danh » va dinh, va dan, va hanh
ky tang » ky nang, ky dang, kho tang
te sach » toc sach
ma hoi » mai hoi, xa hoi, ma hoa
y tang » 6 tang, 7 tang, 5 tang
loc va » hoc va, luc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ((y tang) or (ky tang)) ma hoi. hieu van cham loc va danh dau ((va triet) OR (va trien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((y tang) OR (ky tang)) ma hoi. hieu van cham loc va danh dau ((va triet) OR (va trien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((y tang) or (ky tang)) ma hoi. hieu van cham loc va danh dau ((va triet) OR (va trien))".
• Adding a wildcard symbol may retrieve word variants: te sach ((y tang) or (ky tang)) ma hoi. hieu van cham loc va danh dau ((va triet) OR (va trien))*.