Conflicting definitions of Lewis acids
Moeller's Inorganic Chemistry textbook from 1952 has a fairly long discussion of different theories of acids, citing a lot of primary literature. For Lewis acids, it cites some reviews by W. F. Luder from the 1940's and some of Lewis' original work. Specifically, it says that Lewis in a paper in 1938 (J Franklin Inst. 226:293) described "phenomonological criteria" for Lewis acids and bases, which include the ability to displace weaker Lewis acids and bases. 

My impression from Moeller's description of Lewis' work is thus that he defines an acid as a molecule in which one atom has an incomplete valence shell of electrons. He further views a Bronsted acid as a complex between a Lewis acid ($\ce{H+}$) and a Lewis base (the conjugate base). In a reaction like $\ce{NH3 + AcOH -&gt; NH4+ + AcO-}$, he would say that the stronger Lewis base $\ce{NH3}$ is displacing the weaker Lewis base acetate from the Lewis acid $\ce{H+}$.

If I have time, I'll try to dig up some of those primary sources. Here's a quick list if anyone else wants to go after them:


G. N. Lewis; Valence and the Structure of Atoms and Molecules. The chemical catalog co. (1923)
G. N. Lewis; J Franklin Inst 226:293 (1938)
W. F. Luder; Chem Rev 27:547 (1940)
W. F. Luder and S. Zuffanti; The Electronic Theory of Acids and Bases, Wiley and Sons (1946)
W. F. Luder, W. S. McGuire and S. Zuffanti; J. Chem. Ed. 20:344 (1943)
W. F. Luder; J. Chem. Ed. 22:301 (1945)


UPDATE: The original 1923 Lewis text is available for free from Google Books here:https://books.google.com/books?id=2hxDAAAAIAAJ&amp;printsec=frontcover&amp;source=gbs_ge_summary_r&amp;cad=0#v=onepage&amp;q&amp;f=false

The most relevant passage is from p.142: