The radical character 又's ancient form is a pictogram of a right hand from which the modern Chinese character 右 (right) was derived. Though 又 (again) as a modern Chinese character no longer represents the meaning of "right", the implication of "hand" is preserved in some Chinese characters fall under radical 29.
Fazzioli, Edoardo (1987). Chinese calligraphy : from pictograph to ideogram : the history of 214 essential Chinese/Japanese characters. calligraphy by Rebecca Hon Ko. New York: Abbeville Press. ISBN0-89659-774-1.
GF 0011-2009 Table of Indexing Chinese Character Components prescribes 201 principle indexing components and 100 associated indexing components (in brackets) used in Simplified Chinese. Not all associated indexing components are listed above.