\documentclass[10pt,letterpaper]{article}
\usepackage[paper=letterpaper, text={7in,9.2in},centering]{geometry}
\pagestyle{plain}
\date{}
\makeatletter %
   \renewcommand{\@biblabel}[1]{\textbf{\textsf{#1.}}}    %% Redefine this to get rid of the square brackets around bibliography labels.
\makeatother

\begin{document}

\cite{Holzwarth}\cite{Bertsch}\cite{Woude}\cite{Smolanzuk}

\bibliographystyle{example1}
\bibliography{example1}

\end{document}

