Perhaps you should try some spelling variations:
sach thi » sach thu, sach tai, sach thieu
trinh di » trinh do, trinh dien, trinh dinh
hieu van » hieu va, thien van, lieu va
te sach » toc sach
tinh di » tinh doi, tinh da, tin di
van cac » van hac, van cau, van bac
cua tre » cua te, cuu tre, cua triet
cac luc » cau luc, coc luc, cac nuoc
luc va » duc va, tuc va, loc va
hang x » hoang xa, chang xu, hang nxb

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