There are several records of the density of di-n-butyl ether and n-butyl propionate at 0°C, with the latter dating back to 1886. The preferred melting point for m-hydroxybenzaldehyde is that of Jowett (1900), later identified as p-hydroxyacetophenone, with ample corroboration. Cross-references help avoid duplication and discrepancies, though some sulpha drugs and their acetyl derivatives have conflicting melting points. Natural organic compounds like asarinin, stevioside, and dihydronorguaiaretic acid are missing. Diter-amyl peroxide is listed under A, contrary to its naming. These observations do not imply inaccuracies in the "Dictionary," but show that editors must continually refine their work. The reviewer will continue using the "Dictionary" as a primary source, except for newly described compounds. Linear operators are a modern creation, originating from Hilbert and Riesz's work on integral equations and later developed by Banach, von Neumann, and Stone. The two books discuss different aspects of functional analysis. Zaanen's book covers Lebesgue integral, Lp spaces, Orlicz spaces, and integral equations, while Cooke's focuses on Hilbert space and spectral theory. Zaanen's book is detailed but not suitable for beginners, while Cooke's is a successor to his earlier work, covering Hilbert space, spectral theorem, and Banach algebras. Both books are valuable resources for functional analysis.There are several records of the density of di-n-butyl ether and n-butyl propionate at 0°C, with the latter dating back to 1886. The preferred melting point for m-hydroxybenzaldehyde is that of Jowett (1900), later identified as p-hydroxyacetophenone, with ample corroboration. Cross-references help avoid duplication and discrepancies, though some sulpha drugs and their acetyl derivatives have conflicting melting points. Natural organic compounds like asarinin, stevioside, and dihydronorguaiaretic acid are missing. Diter-amyl peroxide is listed under A, contrary to its naming. These observations do not imply inaccuracies in the "Dictionary," but show that editors must continually refine their work. The reviewer will continue using the "Dictionary" as a primary source, except for newly described compounds. Linear operators are a modern creation, originating from Hilbert and Riesz's work on integral equations and later developed by Banach, von Neumann, and Stone. The two books discuss different aspects of functional analysis. Zaanen's book covers Lebesgue integral, Lp spaces, Orlicz spaces, and integral equations, while Cooke's focuses on Hilbert space and spectral theory. Zaanen's book is detailed but not suitable for beginners, while Cooke's is a successor to his earlier work, covering Hilbert space, spectral theorem, and Banach algebras. Both books are valuable resources for functional analysis.