Perhaps you should try some spelling variations:
thanh vi » hanh vi, thanh va, thanh ve
sach thu » sach thue, sach thieu, sach tham
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
van bac » van ban, van bao, van hac
mang xa » mang may, dang xay, mang cua
lang xa » lang ha, dang xay, lang van
cua tre » cua te, cuu tre, cua triet
xuc va » duc va, luc va, xac va
tuc va » thuc va, truc va, tuc xa
vi cua » vai cua, di cua

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 thu ((lang xa) or (mang xa)) hoi. hieu van bac ((xuc va) OR (tuc va)) thanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach thu ((lang xa) OR (mang xa)) hoi. hieu van bac ((xuc va) OR (tuc va)) thanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach thu ((lang xa) or (mang xa)) hoi. hieu van bac ((xuc va) OR (tuc va)) thanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach thu ((lang xa) or (mang xa)) hoi. hieu van bac ((xuc va) OR (tuc va)) thanh vi cua tre*.