References are transformed in lowercase using IEEbib.bst

Question

I am writing a paper using IEEEbib.bst. I remark that references are changed in lowercase.

\documentclass{article}
\usepackage{spconf,amsmath,graphicx,array}
\usepackage{multicol}
\usepackage{xcolor}
\usepackage{pgf, tikz}
\newcommand{\argmax}{\arg\!\max}
\newcommand{\subfigANDtitle}[2][.2\linewidth]{%
    \begin{tabular}{@{}>{\centering\arraybackslash}p{#1}@{}} #2 \end{tabular}}

% % % % % % % % % % % %
\usepackage{tikz}
\usetikzlibrary{shapes,arrows}
% % % % % % % % % % % %


% Example definitions.
% --------------------
\def\x{{\mathbf x}}
\def\L{{\cal L}}

% Title.
% ------
\title{xxxxyyyyyyyzzzzzzz.}
%
% Single address.
% ---------------
\name{xx,yy}
\address{xxxxxx,yyyyyy}

\begin{document}
    \maketitle
\section{section1}
adaafasfaa \cite{4761608}
\clearpage
\bibliographystyle{IEEEbib}
\bibliography{exbib}
\end{document}