info:oai:utas.edu.au:4064info:ofi/fmt:xml:xsd:journalMcCallumJNMcCallum, JNEllingsenSPEllingsen, SPLovellJEJLovell, JEJ237620070035-8711Magnetic field limits and spectral variability in the Circinus galaxy H2O megamasersMonthly Notices of the Royal Astronomical Society549-556article