Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cua triet, dua tren
thuc va » thuc vat, thuc dan, thuc day
cuu tre » cau tren, cau treo
truc va » thuc vat, trung va
van cau » van dau, van hau, van chat
ty hang » ly hang, ty xang, thi hang
hang o » hang do, hang o2, hoang o
o hoi » co hoi, o hoc, o hai

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 ty hang o hoi. hieu van cau ((truc va) OR (thuc va)) hanh vi ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty hang o hoi. hieu van cau ((truc va) OR (thuc va)) hanh vi ((cua tre) OR (cuu tre))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ty hang o hoi. hieu van cau ((truc va) OR (thuc va)) hanh vi ((cua tre) or (cuu tre))*".