The Bethe-Salpeter amplitude $\mathrm{\ensuremath{\Phi}}(k,p)$ is expressed, by means of the Nakanishi integral representation, via a smooth function $g(\ensuremath{\gamma},z)$. This satisfies canonical equation $g=Ng$. However, calculations kernel $N$ in this equation, presented previously, were restricted to one-boson exchange and, depending on method, dealt with complex multivalued functions...