Perhaps you should try some spelling variations:
hien nhanh » hien hanh, thien thanh, tien thanh
hien xanh » hien hanh, chieu xanh, hien khanh
tranh cua » doanh cua
trong tap » trong thap, tong tap, trong tan
manh cua » doanh cua, ban cua
tap toan » tap doan, tap quan, bai toan
toan cau » 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) OR (hien nhanh)) - hanh ((tranh cua) or (manh cua)) dung trong tap toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hien xanh) OR (hien nhanh)) - hanh ((tranh cua) OR (manh cua)) dung trong tap toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hien xanh) OR (hien nhanh)) - hanh ((tranh cua) or (manh cua)) dung trong tap toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((hien xanh) OR (hien nhanh)) - hanh ((tranh cua) or (manh cua)) dung trong tap toan cau*.