Perhaps you should try some spelling variations:
ban hanh » ban hang
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
duc ban » duc tan, duc van, dua ban
cau duc » cao duc, cau luc, chu duc
van cau » van dau, van hau, van chat
cua tre » cua te, cuu tre, cua triet
lang ha » long ha
ky lang » ky nang, ky dang, ky tang
vu sach » vu bach, su sach, vu khach
vi cua » vai cua, di cua
ha hoi » hoa hoi, ha noi, xa hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((((tu sach) or (vu sach))) or (thuat toan)) ky lang ha hoi. hieu van cau duc ban hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((((tu sach) OR (vu sach))) OR (thuat toan)) ky lang ha hoi. hieu van cau duc ban hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((((tu sach) or (vu sach))) or (thuat toan)) ky lang ha hoi. hieu van cau duc ban hanh vi cua tre*.