I was rummaging around the Internet Archive, a little while ago, and found the first edition of Wayne Grudem's
Systematic Theology: An Introduction to Biblical Doctrine. Amazingly, it is not just a loaner, but is
free--you get to keep it.
This 1994 edition is still available for sale, at least at Amazon. It is a $40 ebook there!
There is a second edition of this book (it is
not free from the Internet Archive) at Amazon. Don't let this necessarily put you off--sometimes a first edition of a book is actually better than (a) subsequent edition(s). And the facts on this subject of this book do not change much over the years.
The book ostensibly is available in several formats, including PDF, ePub, and mobi. The PDF looks fine; the mobi is a mess. I can't say how the ePub turns out, because I haven't been able to open an ePub on my computer, for some reason.
Here is the direct web address for the book.