Perhaps you should try some spelling variations:
land planning » based planning, road planning, dam planning
planning gain » planning chain, planning against, planning guide
gain change » chain change, main changes, can change
using tik » using ti, using time, using task
tung xuan » truong xuan
hong hai » shang hai, zhong tai, dang hai

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: land planning gain change models using tik ((tung xuan) OR (hong hai)) ;~.
• Adding a wildcard symbol may retrieve word variants: land planning gain change models using tik ((tung xuan) or (hong hai)) ;*.