The Phenotype of Axial Spondyloarthritis: Is It Dependent on HLA–B27 Status? (2021)
https://onlinelibrary.wiley.com/doi/abs/10.1002/acr.24174

Efficacy of guselkumab on axial involvement in patients with active psoriatic arthritis and sacroiliitis: a post-hoc analysis of the phase 3 DISCOVER-1 and DISCOVER-2 studies (2021)
https://www.sciencedirect.com/science/article/pii/S2665991321001053

Axial disease in psoriatic arthritis (2020)
https://academic.oup.com/rheumatology/article/59/6/1193/5686423

Efficacy of Ustekinumab on Spondylitis-Associated Endpoints in TNF-naïve Active Psoriatic Arthritis Patients with Physician-Reported Spondylitis (2018)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7046941/?report=reader