0) edge \[shorten &lt;= 0pt, shorten &gt;= 0pt\] node\[above\] [ ]{} (C0); (B0) edge \[shorten &lt;= 0pt, shorten &gt;= 0pt\] node\[above\] [ ]{} (D0); (B0) edge \[shorten &lt;= 0pt, shorten &gt;= 0pt\] node\[above\] [ ]{} (C0); (D0) edge \[shorten &lt;= 0pt, shorten &gt;= 0pt\] node\[above \][ ]{} (C0); (D0) edge \[shorten &lt;= 0pt, shorten &gt;= 0pt\] node\[above \][ ]{} (A