Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hanh vii » hanh voi, hanh va, hanh noi
duc van » duc va, duc tan, duc manh
cau duc » cao duc, cau luc, chu duc
sach ty » sach tu, sach thu, xach tay
van cau » van dau, van hau, van chat
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa

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 ty) or (sach y)) nang ma hoi. hieu van cau duc van ((hanh vii) or (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach y)) nang ma hoi. hieu van cau duc van ((hanh vii) OR (hanh vi)) cua tre.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) or (sach y)) nang ma hoi. hieu van cau duc van ((hanh vii) or (hanh vi)) cua tre*.