Perhaps you should try some spelling variations:
hanh trinh » canh tranh
dung cong » dung trong
cong sach » ong sach, song sach, duong sach
sach toan » hach toan, sach tranh, hoach toan
doc hieu » hoc thieu, hoc hien
qua dung » quang dung, su dung, qua song
toan cao » toan ban, toan tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((doc hieu) or (toc thieu)) xanh - ((hanh trinh) OR (hanh chinh)) qua dung cong sach toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc hieu) OR (toc thieu)) xanh - ((hanh trinh) OR (hanh chinh)) qua dung cong sach toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doc hieu) or (toc thieu)) xanh - ((hanh trinh) OR (hanh chinh)) qua dung cong sach toan cao".
• Adding a wildcard symbol may retrieve word variants: ((doc hieu) or (toc thieu)) xanh - ((hanh trinh) OR (hanh chinh)) qua dung cong sach toan cao*.