Got my hands on an official Call of Duty Zombies 2017 calendar! It features an official concept art piece from either BO2 or BO3 for each month. The images seen here are concept pieces that are exclusive to this calendar. All other months, if you are curious, can be see on the back of the calendar in the last photo.
Also, it is good to note that the second image (the one for August) says it is concept for Buried, however, i am convinced that it is concept for the Crazy Place from BO2’s Origins. This is most likely an error on the publisher’s behalf.