He discovered his vocation to philosophy when he read Husserl's Logical Investigations and abandoned the medical studies he had just begun.

Logical Investigations, 2nd ed.

In the first part of his two-volume work, the Logical Investigations (1901), he launched an extended attack on psychologism.

I studied, under my professors, a good deal of Husserl and his contemporaries but especially the Logical Investigations.

Logical Investigations helped to create phenomenology, and has been credited with making twentieth century continental philosophy possible.

Logical Investigations has been credited with making twentieth century continental philosophy possible.

Nevertheless, the Logical Investigations impressed Heidegger and convinced him to study philosophy.

Sokolowksi notes that between 1900 and 1910, Husserl abandoned the Kantian distinctions made in Logical Investigations.

Husserl's Logical Investigations (1900-1901) is considered the starting point for the formal theory of wholes and their parts known as mereology.

Logical Investigations, 1918 ff.