Here is one possible way to draw your diagram. The AMScd package doesn't seem to support longer arrows, so 7 has to make quite an Odyssey. $\require{AMScd}$ \begin{CD} 7 @= 7 @= 7 @= 7\\ @| @. @. @AyAA\\ 7 @. @. 1 @>x>> 2 @>y>>8\\ @VxVV @. @AxAA @VxVV @VyVV\\ 6 @>x>> 5 @<y<< 4 @<x<< 3 @. 9\\ @VyVV @. @. @VyVV @VxVV\\ 14 @<x<< 13 @>y>> 12 @>x>> 11 @>y>> 10 \end{CD} For a guide to drawing these, see [this MSE meta answer](http://meta.math.stackexchange.com/a/16888/166535). To see the source code, right click over the diagram and choose "Show Math As" > "TeX Commands" or click the edit button to see the source of the whole post.