Who participates in computer science education studies? A literature review on K-12 subjects. - Anna van der Meulen; Felienne Hermans; Efthimia Aivaloglou; Marlies Aldewereld; Bart Heemskerk; Marileen Smit; Alaaeddin Swidan; Charlotte Thepass; Shirley de Wit (PeerJ Comput. Sci., 2021)