Perhaps you should try some spelling variations:
sach thi » sach thu, sach tai, sach thieu
thi hang » thi hanh, thi nang, thi hong
cau treo » cau theo, cau tren, cau triet
trinh di » trinh do, trinh dien, trinh dinh
te sach » toc sach
tinh di » tinh doi, tinh da, tin di
cac loc » cac lop, cac toc, cac hoc
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
loc va » hoc va, luc va
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.

• If you are trying to use Boolean operators, they must be ALL CAPS: te sach thi hang o hoi. hieu va cac loc va ((tinh di) OR (trinh di)) ((cau treo) OR (cua tre))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach thi hang o hoi. hieu va cac loc va ((tinh di) OR (trinh di)) ((cau treo) or (cua tre))~".
• Adding a wildcard symbol may retrieve word variants: te sach thi hang o hoi. hieu va cac loc va ((tinh di) OR (trinh di)) ((cau treo) or (cua tre))*.