Just for the sake of continuity, here are the cover blurbs and images for books 3 and 4!
Book 3
Book 3: Earth Song: The Lost Aria
After more than five centuries of isolation on humanity’s adopted home world, war has come once again. Minu Alma distinguished herself during the Rasa Vendetta and is now charged with creating an army to defend their world. Though the soldiers are untried, she must lead them into battle against a powerful species of the Concordia in the greatest test of her life. Minu must quickly secure victory as she hopes to venture into the galactic frontier. Somewhere out there is an ancient artifact left by a mysterious race called “The Lost” which could unlock all the miracles of Concordian science. She must locate the artifact before time runs out to save her friend, but what she finds will change her life forever. This is The Lost Aria
Book 4: Earth Song: `Etude to War
Chosen. Warrior. Detective? Six years after Minu Groves’ return from her galaxy-spanning quest, she has become a member of the Chosen council – but due to conflicts with others on that council, she’s been put into virtual retirement as a university dean. Until one day, when she learns a truth about her long-missing father that shakes her to the core. Is he still alive? Clues lead into the darkness of space, and once more she and her friends have answers to seek out, a trail to follow that he may have left. And in her absence, clouds of war begin to loom…