Re: Here's books / Here are books.
Here's and there's are not uncommonly followed by a plural noun in informal conversation, but I would not recommend that learners use these forms.
The full forms here is and there is are rarely followed by plural nouns.
The forms here are and there are are rarely contracted in writing.
Even the correct form, "Here are books" sounds unnatural. We'd normally say, "Here are some books".
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