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

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 (thuc vat)) thanh mai va triet~.
• 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 (thuc vat)) thanh mai va triet.
• Adding a wildcard symbol may retrieve word variants: vu sach ky sang mai hoi. hieu van cam ((duc va) or (thuc vat)) thanh mai va triet*.