The book Applied Metamodelling: A Foundation for Language Driven Development continues to be cited in scholarly articles (here is a list since 2014) even though there is no official means of referencing it. A third edition has been created and registered with arXiv (identifier 1505.00149) to provide a permanent record of the book that can be cited:
@ARTICLE{2015arXiv150500149C, author = {{Clark}, T. and {Sammut}, P. and {Willans}, J.}, title = "{Applied Metamodelling: A Foundation for Language Driven Development (Third Edition)}", journal = {ArXiv e-prints}, archivePrefix = "arXiv", eprint = {1505.00149}, primaryClass = "cs.SE", keywords = {Computer Science - Software Engineering}, year = 2015, month = may, adsurl = {http://adsabs.harvard.edu/abs/2015arXiv150500149C}, adsnote = {Provided by the SAO/NASA Astrophysics Data System} }