Lücking, Robert (2020). "Three challenges to contemporaneous taxonomy from a licheno-mycological perspective". Megataxa. 1 (1): 78–103. doi:10.11646/megataxa.1.1.16.
Printzen, Christian (2008). "Klaus Kalb Honored for The Good Use of His Idle Hours Andreas Frisch, Ute Lange, Bettina Staiger . 2007. Lichenologische Nebenstunden: Contributions to lichen taxonomy and ecology in honour of Klaus Kalb. Bibliotheca Lichenologica 96. 343 pp., with 110 figures and 14 tables. J. Cramer. Berlin, Stuttgart, Germany. ISBN: 978-3-443-58075-9. ISSN: 1436-1698 (Series). Price €74.00 + shipping and postage (softcover)". The Bryologist. 111 (4): 686–687. doi:10.1639/0007-2745-111.4.686. S2CID86148750.
Bungartz, Frank; Elix, John A.; Printzen, Christian (2020). "Lecanoroid lichens in the Galapagos Islands: the genera Lecanora, Protoparmeliopsis, and Vainionora (Lecanoraceae, Lecanoromycetes)". Phytotaxa. 431 (1): 1–85. doi:10.11646/phytotaxa.431.1.1. S2CID214377775.
Printzen, Christian (2008). "Klaus Kalb Honored for The Good Use of His Idle Hours Andreas Frisch, Ute Lange, Bettina Staiger . 2007. Lichenologische Nebenstunden: Contributions to lichen taxonomy and ecology in honour of Klaus Kalb. Bibliotheca Lichenologica 96. 343 pp., with 110 figures and 14 tables. J. Cramer. Berlin, Stuttgart, Germany. ISBN: 978-3-443-58075-9. ISSN: 1436-1698 (Series). Price €74.00 + shipping and postage (softcover)". The Bryologist. 111 (4): 686–687. doi:10.1639/0007-2745-111.4.686. S2CID86148750.
Bungartz, Frank; Elix, John A.; Printzen, Christian (2020). "Lecanoroid lichens in the Galapagos Islands: the genera Lecanora, Protoparmeliopsis, and Vainionora (Lecanoraceae, Lecanoromycetes)". Phytotaxa. 431 (1): 1–85. doi:10.11646/phytotaxa.431.1.1. S2CID214377775.