1818, William Jackson Hooker, Musci Exotici; Containing Figures and Descriptions of New or Little Known Foreign Mosses and Other Cryptogamic Subjects:
[…] was given a Jungermannia which, like the present figure, had saccate or hollow claviform appendages, both upon the lesser lobe of the leaves and upon the stipules.
2016, A George, "Hidden symbols", in New Scientist:
“Of course they mean something,” says French prehistorian Jean Clottes. “They didn't do it for fun.” The multiple repetitions of the P-shaped claviform sign in France's Niaux cave “can't be a coincidence”, he argues.
2020, Gudrun Wolfschmidt, Maß und Mythos, Zahl und Zauber - Die Vermessung von Himmel und Erde: Tagung der Gesellschaft für Archäoastronomie in Dortmund 2018. Nuncius Hamburgensis; Band 48, tredition (→ISBN):
Among the inventory of cave paintings, claviform signs, whose shape is reminiscent of the letter 'P' in the Latin alphabet (or the reverse form), form a rather distinctive group.
2012, R Bégouën, C Fritz, G Tosello, Parietal Art and Archaeological Context:
In front of the observer, the end of this tunnel-shaped passage has a series of claviforms (a characteristic geometric form that can be described as a kind of shouldered “sign”) aligned on either side […] Another series includes at least three claviforms and three bars […]
2016, Mark Pizzato Ph.D., Beast-People Onscreen and in Your Brain: […], ABC-CLIO (→ISBN), page 69:
Moving into the depths one finds: triangles (perhaps akin to the vulva or hoof marks in Tito Bustillo), bison and a horse that involve the natural concave surfaces, abstract outlines and repeated “claviforms” (key or club shapes like the letter “P”), […]
2018, DG Maidagan, "New Insights into the Study of Paleolithic Rock Art: Dismantling the “Basque Country Void”", in the Journal of Anthropological Research:
This unique find for the Cantabrian region reflects themes (felines), conventions (use of scraping to show fur), and signs (P-shaped claviforms) that are all more typical of French Pyrenean art than that of northern Spain.
1996, Andrew Lock, Charles R. Peters, Handbook of Human Symbolic Evolution, Oxford University Press
The so-called 'signs' were originally given names that imply shape, such as 'roof-like ' (tectiforms) or 'key-like' (claviforms), although many were named in more obviously interpretative ways, such as 'wounds', 'traps', or 'huts'.
