This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Two exact sequences. math morphism between two short exact sequences Own user AxelBoldt Created by Xypic using the source code below Both the image and the source code are in the public domain Produce postscript file from this input with tex and dvips Loading the XYPic package input xy xyoption all Using postscript driver for smoother