Great news: two of my favorite young adult novels of recent years are now in paperback. First is Steven Gould’s 7th Sigma, a spectacular science fiction/western mashup set in the southwest after a mysterious alien invasion makes it impossible to use metal anywhere in the desert. Next is Paolo Bacigalupi’s Ship Breaker, a brilliant post-peak-oil eco-catastrophe dystopia that matches 7th Sigma for incredible, voracious, unstoppable plotting.