\newbox\sizetestbox
\savebox\sizetestbox{\lstinline|\\cite[See chapter 3 of][]\{mysource\}|}

\newlength\columnfakewidth
\setlength\columnfakewidth{\wd\sizetestbox}
%\setlength\columnfakewidth{\dimexpr\columnfakewidth + 1em\relax}

%\newcommand\firstpart[1]{\atleastwidth[5cm]{#1}}
\newcommand\firstpart[1]{\atleastwidth[\columnfakewidth]{#1}}


\begin{frame}[<+->]{Citeren}
	Variaties in gebruik:
	
	%	\begin{tabular}{ll}
	%		\lstinline|\\cite\{mysource\}|&[1]\\
	%		\only<2->{\lstinline|\\cite[21]\{mysource\}|&[1, p. 21]\\}
	%		\only<3->{\lstinline|\\cite[21--30,8]\{mysource\}|& [1, pp. 21--30, 8]\\}
	%		\only<4->{\lstinline|\\cite[See][21--30,8]\{mysource\}|& [See 1, pp. 21--30, 8]\\}
	%		\only<5->{\lstinline|\\cite[See chapter 3 of][]\{mysource\}|& [See chapter 3 of 1]\\}
	%		\only<6->{\lstinline|\\cite[See chapter 3 of]\{mysource\}|& [1, See chapter 3 of]\\}
	%		\phantom{\lstinline|\\cite[See chapter 3 of]\{mysource\}|}&\phantom{[1, See chapter 3 of]}
	%	\end{tabular}
	\begin{itemize}[label=\textbullet]
		\item \firstpart{\lstinline|\\cite\{mysource\}|}  [1]
		\item \firstpart{\lstinline|\\cite[21]\{mysource\}|}  [1, p. 21]
		\item \firstpart{\lstinline|\\cite[21--30,8]\{mysource\}|}  [1, pp. 21--30, 8]
		\item \firstpart{\lstinline|\\cite[See][21--30,8]\{mysource\}|}  [See 1, pp. 21--30, 8]
		\item \firstpart{\lstinline|\\cite[See chapter 3 of][]\{mysource\}|}  [See chapter 3 of 1]
		\item \firstpart{\lstinline|\\cite[See chapter 3 of]\{mysource\}|}  [1, See chapter 3 of]
		\item \firstpart{\lstinline|\\cites\{mysource\}\{othsource\}|}  [1, 7]
	\end{itemize}
	
\end{frame}