The source is an article from Prince of Travel, a travel blog focused on luxury travel, which provides advice on how to book "impossible" award flights, which are flights that are difficult or unlikely to book using points. The author discusses various strategies for securing these flights, including being flexible with travel dates, having transferable points currencies, understanding when airlines typically release award space, and anticipating schedule changes. Additionally, the author emphasizes the importance of having a robust search strategy and considers using paid services that provide alerts for available award space. The article concludes by suggesting that while booking "impossible" award flights can be challenging, it is often more rewarding than booking more easily attainable flights.