not only (but) (also)

[sitifan]

not only ... but (also) ... both ... and ...: He not only read the book, but also remembered what he had read.
Page 1041, Oxford Advanced Learner's Dictionary
not only ... (but) also ... used to emphasize that sth else is also true: She not only wrote the text but also selected the illustrations.
Page 1037, Oxford Advanced Learner's Dictionary
Which can be omitted: but, also or either word?

Thank you very much for your reply.

[hector51]

you can omit "also"

my 2 cents

[sitifan]

not only ... but also

[Soup]

not only ... but (also)
Leaving out the also from this construction tends to intensify the first part of the construction rather than supplement it:

• • She is not only smart but brilliant.
  • He not only wanted the diamond but wanted it desperately.

Source § 5. not only … but also. 2. Style. The American Heritage Book of English Usage. 1996