Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
duoc lam » duoc pham, duoc ly, duoc li
hieu van » hieu va, thien van, lieu va
ly vang » ly hang, ly van, ly quang
lo vang » lo van, hoa vang
hanh va » hang va, hanh vi
cua tre » cua te, cuu tre, cua triet
va cua » va chua, via cua, ca cua
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ((lo vang) OR (ly vang)) x hoi. hieu van nam ((duoc ma) or (duoc lam)) hanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ((lo vang) OR (ly vang)) x hoi. hieu van nam ((duoc ma) OR (duoc lam)) hanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ((lo vang) OR (ly vang)) x hoi. hieu van nam ((duoc ma) or (duoc lam)) hanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ((lo vang) OR (ly vang)) x hoi. hieu van nam ((duoc ma) or (duoc lam)) hanh va cua tre*.