Fortson, Benjamin W. (2004). Indo-European Language and Culture: An Introduction. Blackwell Publishing. ISBN 1405103167.
Sihler, Andrew L. (1995). New Comparative Grammar of Greek and Latin. New York, Oxford: Oxford University Press. ISBN 0195083458.
Watkins, Calvert (2000). The American Heritage Dictionary of Indo-European Roots (Second Ed.). Boston, New York: Houghton Mifflin Company. ISBN 0618082506.
Pokorny, Julius (1959). Indogermanisches Etymologisches Wörterbuch
Oldest form *eǵ in Watkins and Pokorny, *eǵō or *eǵoH in Sihler, *eǵoH₂ in Fortson.
*H₁me-
Oldest form *me- in Watkins and Pokorny, *me in Sihler, *me- (sometimes extended to *eme-) in Fortson.
*wei-
Oldest form *we- in Watkins, *aw(e)- in Pokorny, *we(i)- in Fortson. *wei- allegedly from Beekes.
*nes-
Oldest form *nes- in Watkins, *ne- in Pokorny, *nos in Sihler, *nes in Fortson.
*tuH-
Oldest form *tu- in Watkins, *tu in Pokorny, *ti or *tu in Sihler, *tu- ("the nominative singular was perhaps *tuH, with the laryngeal the source of the long vowel in most of the descendant forms") in Fortson.
*te-
*te in Sihler.
*yuH-
Oldest form *yu- in Watkins and Pokorny, *yūs (*yuHs noted with question mark) in Sihler.
*wos-
Oldest form *wos- in Watkins, Sihler, Fortson.
*kʷo-
Oldest forms *kʷo- and *kʷi- in Watkins, Pokorny and Fortson, *kʷi-, *kʷe- and kʷo- in Sihler.
*s(w)e-
Oldest form *s(w)e- in Watkins, *se- in Pokorny, *swe- and *se- in Fortson.
*H₂el-
Oldest form *H₂el- (with caveat "probably") in Watkins, Sihler.
Oldest form *oi-no in Watkins, *e- in Pokorny, *oy-no- in Sihler, *oi- (commonly suffixed as *oi-no-) in Fortson.
*sem-
Oldest form *sem- in Watkins, Pokorny, Sihler, Fortson.
*dwo-
Oldest form *dwo- in Watkins, *duō(u) in Pokorny, *duwo in Sihler (originally **dewo or similar), *d(u)woH₁ in Fortson.
*trei-
Oldest form *trei- in Watkins and Pokorny, *treyes in Sihler and Fortson.
*kʷetwer-
Oldest form *kʷetwer- in Watkins, Pokorny, *kʷetwor- in Sihler, *kʷetwores in Fortson.
*penkʷe
Oldest form *penkʷe in Watkins, Pokorny, Sihler, Fortson.
*s(w)eḱs
Oldest form *s(w)eḱs- in Watkins, Pokorny, Sihler (Sihler theorizes that the original form was *weḱs, and s was added to the beginning of the word, sometimes replacing the original w, by way of association with septm̥, Fortson), *sweḱs- in Fortson.
*septm̥
Oldest form *septm̥ in Watkins, Pokorny, Sihler, Fortson.
*H₃eḱteH₃
Oldest form *oḱtō(u) in Watkins, Pokorny and Fortson. According to Sihler, "the evidence of the daughter languages is clear in its general outlines but polyambiguous in detail, which allows for various reconstructions", most likely *H₃eḱtow, but possibly *H₃eḱteH₃ or *H₃eḱtoH₁ (much less likely, because the other numerals 3–10 all have e-grade, are *oḱtō, *oḱtoH₁, *oḱteH₃, *H₁oḱteH₃ or *H₃oḱteH₃).
*(H₁)newn̥
Oldest form *newn̥ in Watkins, Sihler (but Sihler mentions that *H₁newn̥ is used by those who trace prothetic vowels in Greek to laryngeals) and Fortson, *e-newen in Pokorny.
*deḱm̥(t)
Oldest form *deḱm̥ in Watkins, Pokorny, Sihler (but Sihler notes that *deḱm̥t is strongly implied by the ordinal *d(e)ḱm̥t-o- and the decad element **-dkomt) and Fortson.
*wiHḱm̥tiH
Oldest form *wīḱm̥tī- in Watkins, *wī-ḱm̥t-ī in Pokorny, *wīḱm̥t- in Sihler (traced to earlier **wi-dḱomt), *wīḱm̥tī in Fortson (with the caveat "stricly speaking, the comparative evidence only supports a reconstruction *wiḱn̥tī", but that most handbooks give the aforementioned form based on the assumption that this form is derived from *dwiH₁-dḱm̥t-iH₁, "two tens").
*ḱm̥tom
Oldest form *ḱm̥tom in Watkins, Sihler, Fortson.
*teus-ḱm̥ti
No references.
*ǵʰeslo-
Oldest form *ǵʰeslo- in Watkins, Pokorny, Sihler.
*per-
Oldest form *per in Watkins and Pokorny, *preH₃ or *pro (or possibly *proH₂) in Sihler, *perH₃- in Fortson.
Oldest forms *man- and *mon- in Watkins, *manu-s in Pokorny, *manu- in Fortson.
*neH₃-m̥n
Oldest form *H₁no(H₃)-m̥n in Watkins, *en(o)m̥n in Pokorny, (H)nomn̥ or nomn̥ in Sihler. According to Fortson, "a very widespread neuter n-stem noun is the word for 'name', but its precise reconstruction is disputed; two commonly adduced contenders are *H₁neH₃mn̥ and *H₃nomn̥."
*wiH₁-ro-
Oldest form *wiH-ro- in Watkins and Fortson, *wiro-s in Pokorny, *wiros in Sihler.
*gʷen-
Oldest form *gʷen- in Watkins and Fortson, *gʷenā in Pokorny, *gʷenH₂ in Sihler.
*H₂en-
Oldest form *an- in Watkins, *an- in Pokorny.
*pH₂ter-
Oldest form *pH₂ter- in Watkins and Fortson (non-root form *pH₂tēr), *pH₂tē(r) in Pokorny, *pH̥₂tēr or *pH̥₂ter in Sihler.
*meH₂ter-
Oldest form *māter- in Watkins, Pokorny and Fortson (non-root form *mātēr), *ma-H₂ter- in Sihler.
*bʰreH₂ter-
Oldest form *bʰrāter- in Watkins, Pokorny and Fortson, *bʰraH₂ter- in Sihler.
*swesor-
Oldest form *swesor- in Watkins, Pokorny, Sihler and Fortson (non-root form *swesōr).
*sunu-
A derivative noun (*su(H)-nu-) from the verb *seHe- ("to give birth") in Watkins and Fortson, *seu- in Pokorny.
*dʰugH₂ter-
Oldest form *dʰugH₂ter- in Watkins and Fortson, *d(ʰ)ugH₂ter- in Pokorny.
*daiwer-
Oldest form *daiwer- in Watkins, *daiwēr in Pokorny.
*sweḱruH
Oldest form *sweḱuro- in Fortson.
*snus-os
Oldest form *snusos in Fortson.
*ǵH₂lōu-
No references.
*yenH₂ter-
No references.
H₂ewon-
Oldest form *awo- in Watkins, *awo-s in Pokorny.
*nepeH₃t-
Oldest form *nepōt- in Watkins, Pokorny, Fortson.
*widʰeweH₂-
A derivative noun (*widʰ-ewā-) from the verb *weidʰ- ("to divide, separate") in Watkins and Pokorny, *widʰeweH₂ in Fortson.
*gʰosti-
Oldest form *gʰos-ti- in Watkins, *gʰosti-s in Pokorny, *gʰostis in Fortson.
