Looking at Google and Amazon acquisitions, it looks like they pay way more than the textbook value from traditional accounting methods.

There must be a logic behind the price they pay in an acquisition (do they have a magic method, golden ratio?).

Do you have any books or good articles on the subject?

M&A by Amazon: https://en.wikipedia.org/wiki/List_of_mergers_and_acquisitions_by_Amazon M&A by Google: https://en.wikipedia.org/wiki/List_of_mergers_and_acquisitions_by_Alphabet