If you live in Australia my best advice would be to go to your local bookseller, or to the Penguin Random House website. They have a list of booksellers including how to order from your local independent bookseller. Here is the link:
https://www.penguin.com.au/books/the-place-on-dalhousie-9780143793533
If you live outside Australia, I would recommend ordering online at The Book Depository.
https://www.bookdepository.com/Place-on-Dalhousie-Melina-Marchetta/9780143793533?ref=grid-view
The Place on Dalhousie is also available on kindle and audio.
Melina Marchetta 