Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
tinh di » tinh doi, trinh di, tinh da
va tinh » may tinh
cac luc » cau luc, coc luc, cac nuoc
van cac » van hac, van cau, van bac
cua tre » cua te, cuu tre, cua triet
luc va » duc va, tuc va, loc va
hang x » hoang xa, chang xu, hang nxb
di cua » dai cua, doi cua, de cua

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