[starlingdb](https://starlingdb.org/cgi-bin/query.cgi?root=config&morpho=0&basename=\data\ie\piet)
[[r-wescott1993]] Simplified roots
https://en.wiktionary.org/wiki/Category:Proto-Indo-European_lemmas
[[Buck]]
[[Pokorny]]
[[Watkins]]
[[Calin]]
[Wiktionary](https://en.wiktionary.org/wiki/Category:Proto-Indo-European_roots), [Roots by Shape](https://en.wiktionary.org/wiki/Category:Proto-Indo-European_roots_by_shape)