- Profession: Lawyer, liberal-democratic senator in The Hague and Councilor in Amsterdam.
- Residences: Amsterdam, Blaricum.
- Relation to Mahler: No.
- Correspondence with Mahler:
- Born: 10-07-1870 Amsterdam, The Netherlands.
- Died: 24-11-1950 Blaricum, The Netherlands. Aged 80.
- Buried: 28-11-1950 Crematorium Westerveld, Driehuis, Velsen, the Netherlands. Cremated.
Maria Barbera Pijnappel (1870-1950) was married to Charles Ernest Henri Boissevain (1868-1940).
10-03-1906: Zuiderzee: Person number 7 at photo with Gustav Mahler near Zuiderzee.