Leo Nardus (1868-1955) (attributed). Sketchbook with 6 portraits,

black and coloured chalk (1 drawing heightened with white), 4x signed "Nardus" (?) and dated '34-'36, contemporary halfcloth, folio.

Extensively on the interesting artist Leo Nardus (actually Leonardus Salomon or Salomonson): https://tinyurl.com/y7ramkzp.