Perhaps you should try some spelling variations:
dam planning » from planning, land planning, 2 planning
congo call » long call, congo can, congo mali
china tan » china top, china two, china taiwan
sang minh » kang minah, anh minh, song min
tan sang » tan yang, tang tang, tan hong
cong van » congo can, duong van, cong sun

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: ((dam planning) OR (term planning)) can china tan sang minh ((congo call) OR (cong van)) ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((dam planning) OR (term planning)) can china tan sang minh ((congo call) or (cong van)) ;~".
• Adding a wildcard symbol may retrieve word variants: ((dam planning) OR (term planning)) can china tan sang minh ((congo call) or (cong van)) ;*.