Perhaps you should try some spelling variations:
posed variational » based variational, mixed variational, pose variations
labour market » labor market, labor markets
social posed » social power, social post, social posts
oecd labour » forced labour, second labour

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: oecd labour market AND social posed variational problems.
• Adding a wildcard symbol may retrieve word variants: oecd labour market and social posed variational problems*.