D. Bal, “Rediscovery of the Sumatran endemics Onychogomphus rappardi (Odonata: Gomphidae) and Herona sumatrana sumatrana (Lepidoptera: Nymphalidae), with notes on observations of other rare species from the north of Sumatra”, BIO PALEMBANICA, vol. 1, no. 2, pp. 48–58, Dec. 2024.