A typeface with similar contrast which offer polytonic Greek is Scotch Modern: http://www.fontspring.com/fonts/shinntype/scotch-modern/

This is also very close: http://GFS Didot (Bold) by Takis Katsoulidis and George D. Matthiopoulos [2001, part of Google Web Fonts]

GFS Didot (Bold) does indeed have generally matching letter-forms. The major difference is rounded stroke ends and terminals compared to the Einaudi specimen.
I failed to find anything digital that is closer.
don

There is a polytonic version of GFS Didot available from the Greek Font Society http://www.greekfontsociety.gr/pages/en_typefaces20th.html

I don't remember having ever seen before a version of "apla" with square terminals like Einaudi's.

I think the GFS Didot you can download from Google Web Fonts it is polytonic - no need for a special version.
Michel what do you mean by "apla"?

What I know of Greek fonts first comes from the TeX documentation and I understood that the word "apla" was used to refer to that type of Didot font with rolling stress. Here is a link http://www.tex.ac.uk/tex-archive/help/greek/greek.faq and what is said about it

Levy made his Greek fonts after the Didot design, a typeface which was originally created two centuries ago by the famous Didot printers in Paris and which is still used extensively by Greek printers today. Among Greek
printers, this Didot typeface is known as "apla" (plain), but often outsiders call it incorrectly "Greek roman".

A version of Monotype Greek 90 is called Ἁπλᾶ by Haralambous' Atelier Fluxus Virus http://www.polytoniko.org/fonts.php?newlang=en#AFV where Ἁπλᾶ might just mean "regular". So maybe I misinterpreted the documentation though Haralambous in a paper entitled "From Unicode to Typography, a Case Study: the Greek Script", has a subsection 1.7.1 on the apla style where he includes the italic and the bold.

Thanks, although I'm Greek I didn't know that "apla" (απλά) was used to characterize this Didot type and yes the word actually means plain (or simple) in contrast to composite or complex.

Here is a working link on Haralambous' paper http://wenku.baidu.com/view/7b826622af45b307e87197e8.html

It takes a while to load, but it's a very interesting paper ;)
Thanks

Dear TEODF,
I don't know which font this actually is. But I can add that absolutely the same one has been used by Adelphi publisher for some 'older' books, as e.g. La ragione errabonda by Giorgio Colli, up to about 1995. Afterwards, this publishing house used the more ordinary -and, I would add, more ugly- greek series of MS Times New Roman (!).
I know that when wanting something, one wants EXACTLY that; but at least I may suggest something appearing to be inspired by similar approach : provided by the Society of Biblical Literature.
It has the same 'broken' ends, some 'archaicity' in the ductus, but it differs for the light slant to the right and more explicitly in some features, as the theta design.
The hunting goes on

Just to give an exemple of 'older' Adelphi greek font (from Giorgio Colli, la Ragione Errabonda, printed in 1982 still with metal glyphs - you can see some vertical traces between the letters):

Interesting the effect of Baskerville and 'greek' combined in the same text, as in Einaudi Snell.
Some difference in the choosen form of 'rho', but indeed the same font.