I have quite a few old Ikea Billy bookcases in a now discontinued colour called Beech. Two of these are also in the now discontinued width of 60cm and are very handy for those narrower spaces. I have never liked the 40cm wide Billy bookcases and have not bought any.
I have a couple of spaces in the new house which could use a 60cm wide bookcase. So was happy to see the new Ikea GERSBY which is 60cm wide, 24cm deep and 1.8m tall.
Currently no light oak/beech type colours which would be nice and complement my furniture better but these look to be handy.