Perhaps you should try some spelling variations:
sach tranh » canh tranh
hanh trinh » canh tranh, hanh chinh
tranh my » trinh my, tran sy, anh my
trinh do » trinh ky
co sach » bo sach, cuon sach, hoc sach
su hanh » su thanh, du hanh, lu hanh
my khi » ly khi, ky khi, my chi
do khi » doi khi, do thi, co khi

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( co sach tranh my khi đong luc ) or ( su hanh trinh do khi đong luc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( co sach tranh my khi đong luc ) OR ( su hanh trinh do khi đong luc )).
• Adding a wildcard symbol may retrieve word variants: (( co sach tranh my khi đong luc ) or ( su hanh trinh do khi đong luc ))*.