Printed

Mosses and Liverworts of Britain and Ireland – a field guide by L. Atherton, S. Bosanquet and M. Lawley (editors) (British Bryological Society, 2010)

Mosses and Liverworts of Woodlands by Martin Godfrey (Field Studies Council, Wild ID fold-out card, 2014)

Mosses and Liverworts of Towns and Gardens by Martin Godfrey (Field Studies Council, Wild ID fold-out card, 2014)

The Liverwort Flora of The British Isles by Jean A Paton  (Harley Books 1999 / Brill e-book, 626 pages)

Websites

Google Lens: Go to google.com and there is a camera icon at the right of the search bar. Click on this, and you can drag and drop any image and it will do its best to identify it – so can be used for any flora and fauna, vertebrates and invertebrates etc. (as well as buildings, landscapes – anything, in fact.)  Worth a look, but treat identifications with caution!

Apps