Surely Etymonline (as also others noted nearby) - it is sequential (alphabetically of course) as much as hypertextual so it is equivalent to the text of a book;
from the actual "ISBN" titles, without too much of a system but as a preliminary scavenging read you may check:
Justin Cord Hayes - The Unexpected Evolution of Language
and
Nigel Rees - Why Do We Say
(Nigel Rees also being the conductor of the 500 episodes of the radio programme "Quote... Unquote". Very prolific writer, apparently, other titles from him could be relevant).
from the actual "ISBN" titles, without too much of a system but as a preliminary scavenging read you may check:
Justin Cord Hayes - The Unexpected Evolution of Language
and
Nigel Rees - Why Do We Say
(Nigel Rees also being the conductor of the 500 episodes of the radio programme "Quote... Unquote". Very prolific writer, apparently, other titles from him could be relevant).