Where i can to find material about Diffeomorphism Groups as Metric Spaces

Question

My professor give me one document where it speak about Diffeomorphism Groups as Metric Spaces but it does no has calculations and i need to explain something about it.(The reference book is The Geometric of infinite-dimensional Groups, Boris, A and Robert Went) When i research in google do not appear many information, it seems is an actual subject. I would appreciate any help with references please, i am in Brazil, perhaps somebody in other continent has more access to another platforms or something, thank you a lot