You would understand "simplified" would require
some culling of stamps, descriptions etc
to fascilitate size restrictions.
But pity the poor philatelic student trying to organise
his stamps via Gibbons.
Here is an example, the Line Engraved stamp was
produced in late may 1959
The Lithographed issue in 1960
Where does Gibbons list these two stamps?....1929
http://cjoint.com/11oc/AJnfvBIi3fT.htm