Perhaps you should try some spelling variations:
thong tong » thong thong, thong trong, thong cong
trinh cua » trinh luat, trinh quan, trinh luan
ho trieu » mot trieu, 30 trieu, ho chieu
25 trieu » 30 trieu
tinh cua » sinh cua, tinh chat, tranh cua
tong tap » tuong tac, trong tan, cong tac
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.

• If you are trying to use Boolean operators, they must be ALL CAPS: ((ho trieu) OR (25 trieu)) tinh - hanh ((trinh cua) OR (tinh cua)) thong tong tap toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((ho trieu) or (25 trieu)) tinh - hanh ((trinh cua) OR (tinh cua)) thong tong tap toan cau~".
• Adding a wildcard symbol may retrieve word variants: ((ho trieu) or (25 trieu)) tinh - hanh ((trinh cua) OR (tinh cua)) thong tong tap toan cau*.