It suposed to be the "buku" first
"Ini adalah sebuah buku tentang metode ilmiah itu."
That's how it was supposed t
"Buku ini tentang metode ilmiah." benar juga
That would have a slightly different meaning, though... It would mean "This book is about the scientific method", not "This is a book about..."
For a great book about the scientific method, search for "Harry Potter and the Methods of Rationality". There even is an Indonesian translation! It's probably the most awesome book I've read last year.