Perhaps you should try some spelling variations:
estimation algorithms » estimation algorithm, optimization algorithms, optimisation algorithm
parameter estimation » parameter estimates, parameter optimization
source algorithm » our algorithm, search algorithm
models using » model using, models nursing, code using
using source » using force, using morse

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( models using source algorithm ) or ( modified parameter estimation algorithms ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( models using source algorithm ) OR ( modified parameter estimation algorithms )).
• Adding a wildcard symbol may retrieve word variants: (( models using source algorithm ) or ( modified parameter estimation algorithms ))*.