Perhaps you should try some spelling variations:
tinh dai » trinh dai, tinh da, tinh hai
hieu van » hieu va, thien van, lieu va
te sach » toc sach
va tinh » may tinh
cau duc » cao duc, cau luc, chu duc
van cau » van dau, van hau, van chat
cua tre » cua te, cuu tre, cua triet
tu hanh » du hanh, lu hanh, thi hanh
tu hang » thu hang, tu hung, ty hang
o hoi » co hoi, o hoc, o hai

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