Is there a way to have references in the same latex file (i.e. instead of having the references in a separate .bib file)
Yes and no.
You can create your own bibliography manually:
However, this lacks consistency through automation as well as ease-of-maintenance.
A far better alternative to handling a bibliography "within the same file" would be to embed it via the aid of
Here is an example:
In case this is the request of a publisher who wants only one file compiling with standard packages only, the classical way of doing this is:
Send that file
In addition, you may use the amsrefs-package.
According to the documentation, there are three ways of using the package:
Item 1 is the method you are asking for. The amsrefs-package is included in TeX-distributions.