On a new invasion of the kruper's nuthatch Sitta krueperi into the belt of broadleaf forests of the Caucasus

Second edition. First publication: Karavayev A.A., Khubiev A.B. 2012. On the new invasion of the black-headed nuthatch in the belt of the deciduous forests of the Caucasus // Caucasus. ornithol. notable 24: 59-61.