c1 Refereed Journal Article, LL 21/7/14. Journal name is known as: Miskolc Mathematical Notes, Blue in Sherpa: Author's Pre-print: author cannot archive pre-print (ie pre-refereeing) Author's Post-print: author can archive post-print (ie final draft post-refereeing) Publisher's Version/PDF: author can archive publisher's version/PDF General Conditions: •Publisher's version/PDF may be used •On author's personal website •On author or institutional server / repository, Requested (Sofo) Permission 19.9.14-MMM. HERDC documentation added to dark upload - HD 18/2/20