How to change author separator into “\&” if more 3 or more?

Question

I am using a amsrefs bibstyle and I need to count the number of authors.

\documentclass{article}
\usepackage{amsrefs}

\begin{document}
\begin{thebibliography}{9}

\bib{CR1}{article}
{
author={Author},
year={2012},
volume={5},
number={5},
pages={428\ndash{}45}
}

\bib{CR2}{article}
{
author={Author1},
author={Author2},
year={2012},
volume={5},
number={5},
}

\bib{CR3}{article}
{
author={Author1},
author={Author2},
author={Author3},
number={5},
pages={428\ndash{}45}
}

\end{thebibliography}
\end{document}

If 2 authors - separator is "and"

else 3 or more - separator is "&"

Output should be:

[1] Author 5 ( 2012 ),no. 5 , 428{ 45.

[2] Author1 and Author2 5 ( 2012 ),no. 5.

[3] Author1 , Author2 ,& Author3 5 , 428{ 45 .

Answer 1

This can be achieved by modifying \PrintNames@a macro from the package amsref.

MWE:

\documentclass{article}

\usepackage{amsrefs}

\makeatletter
\renewcommand{\PrintNames@a}[4]{%
    \PrintSeries{\name}
        {#1}
        {}{ and \set@othername}
        {,}{ \set@othername}
        %{,}{ and \set@othername}
        {,}{ \& \set@othername}%changed to "\&" from "and" for the customized output 
        {#2}{#4}{#3}%
}
\makeatother

\begin{document}
\begin{thebibliography}{9}

\bib{CR1}{article}
{
author={Author},
year={2012},
volume={5},
number={5},
pages={428\ndash{}45}
}

\bib{CR2}{article}
{
author={Author1},
author={Author2},
year={2012},
volume={5},
number={5},
}

\bib{CR3}{article}
{
author={Author1},
author={Author2},
author={Author3},
number={5},
pages={428\ndash{}45}
}

\end{thebibliography}
\end{document}

Output:

Note: The same change is applicable for Editor presentation as well.