The Golden Encyclopedia Books?

I have the new revised edition, made in 1969 i think. i got them when i was little for christmas from my grandma becuase i had the orig edition of 2 of them and i loved to look at the pictures. So she got me 1-16 of the new revised edition. I wanted to know if there were any differences or any other info. Like how much is it worth.... most likely not much and i dont plan on selling them. I just pulled them out today and i was curious. Also, is there only 16 of them, of is there more?