How to cite authors with same surnames? How should I use in-text citation in case of one book from two authors with same surnames?
For instance; a source from Paul Ehrlich and Anna H. Ehrlich.
Which one is correct?

&quot; ... &quot; (Ehrlich &amp; Ehrlich, 2015)
&quot; ... &quot; (P. Ehrlich &amp; Ehrlich, 2015)
" ... " (Ehrlich &amp; Ehrlich, 2015)
  " ... " (P. Ehrlich &amp; A. H. Ehrlich, 2015)
  " ... " (Paul Ehrlich &amp; Anna H. Ehrlich, 2015)
  


Are all correct. The adopted reference style will dictate which should be used.