Looking for papers and articles on higher-order sequent systems I am looking for work on systems that are similar to K. Dosen's higher-order sequents ("Sequent Systems for Modal Logic", JSL 50).  The only work that I am aware of is recent work by Iemhoff and Metcalfe ("Proof theory for admissible rules", Annals of Pure and Applied Logic 159 (1-2), 2009).

Are there other papers on such systems?
Again I'm not exactly sure what you are looking for because there are potentially many "similar" systems, but for recent work that I think is very related you can read Part II ("Mixing Derivability and Admissibility") of Dan Licata's thesis, as well as Constructive provability logic by Rob Simmons and Bernardo Toninho.