Perhaps you should try some spelling variations:
trading case » trading costs, trade case
wang liang » wang yang
liang yao » yang yao, gang yao, liang dan
du credit » 2 credit
de credit » 2 credit, trade credit
case how » curse how, case h, else how
how shu » how she, how shih, how slum

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "wang liang yao ((du credit) OR (de credit)) trading case how shu ;~".
• Adding a wildcard symbol may retrieve word variants: wang liang yao ((du credit) OR (de credit)) trading case how shu ;*.