I’ve used Joan Boytim’s books “First Book of Solos” for all different singers throughout my teaching career. They are great for first selections for younger singers, and include diverse languages and styles.
Happily I just found them over the weekend collected in spiral-bound volumes. Each collection includes Parts 1, 2, and 3. These are a great resource for me, and I’m excited to get them in a spiral bound (stay-open-on-the-piano) version!