Karakolev, R., Koynarski, T., Petrova-Tsenin, P. and Petrova, R. (2023) “Influence of ‘``Avigen Duck’ Immunomodulator on Some Humoral Factors of Non-specific Protection in White Pekin Ducks Parents”, Proceedings of the Bulgarian Academy of Sciences. Sofia, Bulgaria, 76(6), pp. 970–976. doi: 10.7546/CRABS.2023.06.18.