Perhaps you should try some spelling variations:
dong yang » dong hoang, wang yang, yang yang
sang minh » kang minah, anh minh, song ming
than bad » than bau, than a, than big
can data » can tata, dan data, fan data
song min » song ming, gong min, jong min
yang ka » yang fan, yang yao
how hai » how has, how ai, how hci

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: dong yang ka ((than bad) OR (can data)) ((sang minh) OR (song min)) how hai ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "dong yang ka ((than bad) or (can data)) ((sang minh) OR (song min)) how hai ;~".
• Adding a wildcard symbol may retrieve word variants: dong yang ka ((than bad) or (can data)) ((sang minh) OR (song min)) how hai ;*.