Complex sentence: Hjalmar Marius Pettersen (13 January 1856--18 January 1928) was a Norwegian librarian and bibliographer, best known for editing the "Bibliotheca Norvegica", a bibliography of Norwegian literature.
Split into simpler sentences: Hjalmar Marius Pettersen (13 January 1856--18 January 1928) was a Norwegian librarian and bibliographer. He is best known for having edited the "Bibliotheca Norvegica", a bibliography of Norwegian literature.