In the book "Practical LaTeX" of George Grätzer you can find on page 94 a simular example like that you showed in your question.
\begin{thebibliography}{9}
\bibitem{gM12}%
George~A. Mennuhin, \emph{Universal Algebra},
University Series in Higher Mathematics, vol.~158,
D.~Van Nostrand, Princton, 2012.
\end{thebibliography}
Here the vol.~158
and D.~Van
can make sense because with the usage of \bibitem
the writer of the document has the control for a good layout.
I teach my students (for didactical reasons) always write a ~
where one do not want to get a line break, if it is useless (George~A.
a linebreak should not occur) or not. It is easier to write ~
always than only from time to time where it is needed.
If the bibliography is build via .bib
file I do not write ~
.
With the following MWE (I doubled the \bibitem
to have one with ~
, one without)
\documentclass[11pt]{article} % try with 10pt and 11pt
\usepackage[left=3cm,right=3cm,showframe]{geometry}
\begin{document}
Text~\cite{gM12} Text \cite{gM13} text
\begin{thebibliography}{9}
\bibitem{gM12}%
George~A. Mennuhin, \emph{Universal Algebra},
University Series in Higher Mathematics, vol.~158,
D.~Van Nostrand, Princton, 2012.
\bibitem{gM13}%
George A. Mennuhin, \emph{Universal Algebra},
University Series in Higher Mathematics, vol. 158,
D. Van Nostrand, Princton, 2012.
\end{thebibliography}
\end{document}
I get the resulting pdf:

Marked with the red arrow you can see an usually unwanted line break between vol.
and number 158
. With other parameters for geometry
or fontsize you can get the situation, that a typographic unwanted line break could happen between D.
and Van
. So I think it makes sense writing ~
in bibliographys build with \bibitem
...
bibitem´ without the
~` ? – l7ll7 Apr 13 '16 at 10:54