Lyubomirova, Valentina, Iva Belovezhdova, Alexandra Kamusheva, Petar Ignatov, and Petar Tuhchiev. 2026. “Optimization of Solid-Phase Extraction and GC-MS/MS Determination of PAHs in Bulgarian Sewage Sludge”. Proceedings of the Bulgarian Academy of Sciences 79 (3). Sofia, Bulgaria:312–320. https://doi.org/10.7546/CRABS.2026.03.04.