Perhaps you should try some spelling variations:
hanh vai » hanh vi, hanh tai, hanh van
sach thu » sach thue, sach thieu, sach tham
hieu van » hieu va, thien van, lieu va
dau xua » dau cua, dao xuan, dau luan
hanh va » hang va, hanh vi
xua van » xua va, qua van, cua van
van dau » van dao, phan dau
sach ty » sach y, sach tu, xach tay
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
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: su ((sach ty) OR (sach thu)) nang ma hoi. hieu van dau xua van ((hanh vai) or (hanh va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach thu)) nang ma hoi. hieu van dau xua van ((hanh vai) OR (hanh va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) OR (sach thu)) nang ma hoi. hieu van dau xua van ((hanh vai) or (hanh va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) OR (sach thu)) nang ma hoi. hieu van dau xua van ((hanh vai) or (hanh va)) cua tre*.