Perhaps you should try some spelling variations:
thanh mai » thanh hai, thanh tai, thanh moi
va trien » va truyen, va thiet, va tuyen
sang mai » sang ma, sang tai, lang mai
va triet » va thiet, ve triet, cua triet
hieu van » hieu va, thien van, lieu va
truc va » thuc va, thuc vat, trung va
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
van cam » van nam, van lam, van cau
mai hoi » mai khoi, dai hoi, lai hoi
ky sang » ky nang, ky dang, ky tang

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky sang mai hoi. hieu van cam ((duc va) or (truc va)) thanh mai ((va triet) OR (va trien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky sang mai hoi. hieu van cam ((duc va) OR (truc va)) thanh mai ((va triet) OR (va trien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky sang mai hoi. hieu van cam ((duc va) or (truc va)) thanh mai ((va triet) OR (va trien))".
• Adding a wildcard symbol may retrieve word variants: vu sach ky sang mai hoi. hieu van cam ((duc va) or (truc va)) thanh mai ((va triet) OR (va trien))*.