These are 708 books that must be great because they have survived 4 rounds of mass extinction or mild culling by the editors of "1001 Books You Must Read Before You Die." In recognition of their resilience and staying power, the books have been dubbed the "Core List" in the source article, which has the title 'Differences Between the Original and Current "1,001" Lists.'
DETAILS:
These 708 books were included in the original (2006) edition of "1001 Books to Read Before You Die", and have survived the 1st 4 rounds of culling as follows:
2008: 282 books removed from 2006 edition (282 substitutes in exchange; similar balanced substitutions for following editions)
2010: 11 books removed from 2008 edition
2012: 12 books removed from 2010 edition
2014: 279 books removed from 2012 edition
. . .
2018: 10 books removed from 2014 edition (not accounted for)
One might suspect another large-scale extinction event will occur in the near future, in order to admit more trendy modern works.