Perhaps you should try some spelling variations:
hien nhanh » hien hanh, thien thanh, tien thanh
hien xanh » hien hanh, chieu xanh, hien khanh
hanh tang » hanh trang, anh tang, hanh mang
cua thong » cua thuong, cua khong, cua tong
thong bai » thong tai, nhung bai, thong xay
tang cua » mang cua, hang cua, tang luan
bai toan » bai tap
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 tang cua thong thong bai toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hien xanh) OR (hien nhanh)) - hanh tang cua thong thong bai toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((hien xanh) OR (hien nhanh)) - hanh tang cua thong thong bai toan cau*.