Numerous papers/books(citation needed) refer to the operator $$A\_\lambda := \lambda AR\_\lambda (A) = \lambda^2 R\_\lambda(A) - \lambda I$$ where $R\_\lambda(A)=(I+\lambda A)^{-1}$ is the resolvent, as *Yosida approximation* without indicating the original source of it. 


Can somebody provide the exact source to a Yosida's paper where this operator was originally introduced?



Reference request: Original source of Yosida approximation

> 
> ...It is well known that the celebrated Hille-Yosida theorem,
>  discovered independently by Hille [1] and Yosida [2], gave the first
>  characterization of the infinitesimal generator of a strongly
>  continuous semigroup of contractions. This was the beginning of a
>  systematic development of the theory of semigroups of bounded linear
>  operators. The bounded linear operator $A\_λ$ appearing in the
>  **sufficiency part** of Yosida’s proof of this theorem is called the
>  *Yosida approximation* of $A$... ([3] preface i)
> 
> 
> 


[1] Functional Analysis and Semi-groups, 3rd Print, Amer. Math. Soc. Colloq. Publ. Vol. 31, NY, 1948.


[2] On the differentiability and representation of one parameter semi-groups of linear operators, J. Math. Soc. Japan, 1, 15–21, 1948.


[3] Govindan, T. E. "Yosida Approximations of Stochastic Differential Equations in Infinite Dimensions and Applications." Probability theory and stochastic modelling ( 79 (2016).


