Perhaps you should try some spelling variations:
hinh tai » chinh tai, hinh thai, hinh bai
te sach » toc sach
han tai » hang tai, nhan tai, van tai
cac luc » cau luc, coc luc, cac nuoc
hieu va » lieu va, hieu qua
van hoi » van hoa, van hoc, van hoe
cua tre » cua te, cuu tre, cua triet
y tang » ky tang, 7 tang, 5 tang
luc va » duc va, tuc va, loc va

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 ((y tang) OR (6 tang)) van hoi. hieu va cac luc va ((hinh tai) or (han tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((y tang) OR (6 tang)) van hoi. hieu va cac luc va ((hinh tai) OR (han tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((y tang) OR (6 tang)) van hoi. hieu va cac luc va ((hinh tai) or (han tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ((y tang) OR (6 tang)) van hoi. hieu va cac luc va ((hinh tai) or (han tai)) cua tre*.