Perhaps you should try some spelling variations:
sach thi » sach thu, sach tai, sach thieu
thanh di » thanh doi, thanh de, thanh do
va thanh » gia thanh, ban thanh, va tinh
te sach » toc sach
cuu tre » cau tren, cau treo
cac luc » cau luc, coc luc, cac nuoc
hieu va » lieu va, hieu qua
hang do » hang doi, dang do, hang di
cua tre » cua te, cua triet, dua tren
luc va » duc va, tuc va, loc va
hang o » hang o2, hoang o, thang o

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach thi ((hang o) OR (hang do)) hoi. hieu va cac luc va thanh di ((cuu tre) or (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach thi ((hang o) OR (hang do)) hoi. hieu va cac luc va thanh di ((cuu tre) OR (cua tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach thi ((hang o) OR (hang do)) hoi. hieu va cac luc va thanh di ((cuu tre) or (cua tre))".
• Adding a wildcard symbol may retrieve word variants: te sach thi ((hang o) OR (hang do)) hoi. hieu va cac luc va thanh di ((cuu tre) or (cua tre))*.