documentclass{article}
usepackage [backend=bibtex,style=authoryear]{biblatex}
usepackage{filecontents}
begin{filecontents}{refs.bib}
@article{a,
    title = {first publication},
    journal = {a first journal},
    author = {A},
    year = {2000},
}
@article{b,
    title = {second publication},
    journal = {a second journal},
    author = {X and C},
    year = {1988},
}
@article{c,
    title = {third publication},
    journal = {a third journal},
    author = {O and P and Q},
    year = {2006},
}
@article{h,
    title = {Observations of ingot macrosegregation on model systems},
    journal = {Metallurgical Transactions},
    author = {Hebditch, D. J. and Hunt, J. D.},
    year = {1974},
}
end{filecontents}
addbibresource{refs}
ExecuteBibliographyOptions{ minnames=1, maxnames=2,
                            maxbibnames=20,
                            }

%define label before reference in list
renewbibmacro{begentry}{%
textbf{(printnames[][-value{liststop}]{labelname}~printfield{labelyear}printfield{extrayear}})\}

begin{document}
parencite{a} \
parencite{b} \
parencite{c} \
parencite{h} \
printbibliography
end{document}