Last sea represented in map-books? (7)

I believe the answer is:

atlases

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'books?' is the definition.
(I've seen this before)

'last sea represented in' is the wordplay.
'represented in' is an anagram indicator.
'last'+'sea'='lastsea'
'lastsea' anagrammed gives 'ATLASES'.

'map' is the link.
This may not be correct. It may be part of another bit of the clue.

Can you help me to learn more?

(Other definitions for atlases that I've seen before include "Cartographical works" , "navigation aids" , "Sea salt (anag.)" , "Collected charts" , "Sea-salt (anag)" .)

I've seen this clue in the Sydney Morning Herald.

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