Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
hien xanh » hien hanh, hien nhanh, chieu xanh
tranh van » tran van, trinh van, tranh ban
thanh van » thanh san, thanh toan, thanh phan
tranh va » trang va, trinh va, thanh va
cong bai » cuong bai, cong hai, cung bai
bai toan » bai tap
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: hoc hien xanh - hanh ((tranh va) OR (((tranh van) OR (thanh van)))) nhung cong bai toan cao~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hien xanh - hanh ((tranh va) OR (((tranh van) OR (thanh van)))) nhung cong bai toan cao".
• Adding a wildcard symbol may retrieve word variants: hoc hien xanh - hanh ((tranh va) OR (((tranh van) OR (thanh van)))) nhung cong bai toan cao*.