Perhaps you should try some spelling variations:
"modified coverage approximation algorithms" » "modified average approximation algorithms"
"verified network optimization algorithm" » "verified network optimization algorithms", "verified network optimisation algorithm", "verified network estimation algorithm", "certified network optimization algorithm", "defined network optimization algorithm"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("modified coverage approximation algorithms") OR ("verified network optimization algorithm"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"modified coverage approximation algorithms\") OR (\"verified network optimization algorithm\"))*".
• Removing quotes may allow a broader search: (( modified coverage approximation algorithms ) OR ( verified network optimization algorithm ))*.