If you are going to look for things like this, it's best to understand how it happens, and what it's known to have happened on.
This resource is a good place to start, it's Reverse Design Varieties (RDV) for Lincoln cents, there is also on that site another page for Obverse Design Varities (ODV)http://varietyvista.com/01b%20LC%20...arieties.htm
since 1959 and the Memorial cent
, the mint has tweeked the reverse design a number of times (8). Close and Wide AM die varieties are transitional errors, the switch from one design to another, and the wrong reverse dies were used on the transitional years creating a die variety for that year.
for the Lincoln cent the obverse was used since 1909 with minor changes, this happened 43 times over the years.
Anyways, I found it a useful resource to figure out how to determine the design varieties, and what I am, and am not looking for, along with the DDOs DDRs, and errors.