Petreska Stanoeva, J., Stefova, E., Cvetanoska, M. and Bogdanov, J. 2022. Establishing mass spectral fragmentation patterns for characterization of 1,2 -unsaturated pyrrolizidine alkaloids and N-oxides in Boraginaceae species from Macedonia using LC-ESI-MS/MS. Macedonian Journal of Chemistry and Chemical Engineering. 41, 1 (Jun. 2022). DOI:https://doi.org/10.20450/mjcce.2022.2491.