Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu sang
cong quang » luong quang, thong quang, duong quang
hieu cach » hieu cac, hieu ca, biet cach
hanh mang » nhanh mang, hanh trang, nhanh lang
cong van » cong vang, cong san, song van
toan cao » toan ban, toan tap
mang va » mang vua, hang va, bang va

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((hieu cach) OR (chieu sach)) - hanh mang va nhung ((cong van) or (cong quang)) toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu cach) OR (chieu sach)) - hanh mang va nhung ((cong van) OR (cong quang)) toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu cach) OR (chieu sach)) - hanh mang va nhung ((cong van) or (cong quang)) toan cao".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu cach) OR (chieu sach)) - hanh mang va nhung ((cong van) or (cong quang)) toan cao*.