BioStor
 | Review of the taxonomy of Aster sensu lato (Asteraceae: Astereae), emphasizing the New World species G L Nesom Phytologia 77: 141-297 |
 | Apopyros (Asteraceae: Astereae), a new genus from southern Brazil, Argentina and Paraguay G L Nesom (1994) Phytologia 76: 176-184 |