I knew the first from my own interests rather than it being just what you needed but then found the others, but I'm still not sure whether they are what you want:
Wagg, A. S., Newman, D. K., Leichsenring, K., & van Houten, P. (2014). Developing an internationally-applicable service specification for continence care: Systematic review, evidence synthesis and expert consensus. PloS one, 9(8), e104129.
Rolfe, G. (2006). Validity, trustworthiness and rigour: quality and the idea of qualitative research. Journal of advanced nursing, 53(3), 304-310.
https://www.researchgate.net/publication/7331242
Delaney, A., Tamás, P. A., Crane, T. A., & Chesterman, S. (2016). Systematic Review of Methods in Low-Consensus Fields: Supporting Commensuration through Construct-Centered Methods Aggregation’in the Case of Climate Change Vulnerability Research. PloS one, 11(2), e0149071.
Jones, J., & Hunter, D. (1995). Consensus methods for medical and health services research. BMJ: British Medical Journal, 311(7001), 376.
https://www.researchgate.net/publication/15557703
By the nature on Delphi, I seem to have suggested these from this technique:
Hasson, F., Keeney, S., & McKenna, H. (2000). Research guidelines for the Delphi survey technique. Journal of advanced nursing, 32(4), 1008-1015.
https://www.researchgate.net/publication/12233148
Ahmad, M., Saleh, A., Rayan, A., Bdair, I. A., Batarseh, K., Abuadas, F., ... & Abu-Abboud, N. (2014). Web-based research using Delphi methodology to explore the discrepancy in qualitative research. International Journal of Nursing and Health Sciences, 1(6), 60-68.
Ferri, C. P., Prince, M., Brayne, C., Brodaty, H., Fratiglioni, L., Ganguli, M., ... & Jorm, A. (2006). Global prevalence of dementia: a Delphi consensus study. The lancet, 366(9503), 2112-2117.
https://www.researchgate.net/publication/7409168
van de Glind, I., Berben, S., Zeegers, F., Poppen, H., Hoogeveen, M., Bolt, I., ... & Vloet, L. (2016). A national research agenda for pre-hospital emergency medical services in the Netherlands: a Delphi-study. Scandinavian journal of trauma, resuscitation and emergency medicine, 24(1), 2.