Perhaps you should try some spelling variations:
va trien » va truyen, va thiet, va tuyen
hieu van » hieu va, thien van, lieu va
va hanh » van hanh, va thanh, va danh
cac dai » cac dan, cac bai, can dai
cac dac » cac dan, cac bac, cac tac
so sach » so sanh, bo sach, hoc sach
tang ma » mang may, tang van
ky tang » ky nang, ky dang, kho tang
co sach » bo sach, cuon sach, hoc sach
ma hoi » mai hoi, xa hoi, ma hoa
vi va » vi van, vai va, vu va

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) or (co sach)) ky tang ma hoi. hieu van ((cac dac) or (cac dai)) va hanh vi va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (co sach)) ky tang ma hoi. hieu van ((cac dac) OR (cac dai)) va hanh vi va trien.
• Adding a wildcard symbol may retrieve word variants: ((so sach) or (co sach)) ky tang ma hoi. hieu van ((cac dac) or (cac dai)) va hanh vi va trien*.