Langevich, H. Letter, To: Sister Olya From: Mother Helena Langevich, [n.d.].
Dyfyniad Arddull ChicagoLangevich, Helena. Letter, To: Sister Olya From: Mother Helena Langevich, [n.d.].
Dyfyniad MLALangevich, Helena. Letter, To: Sister Olya From: Mother Helena Langevich, [n.d.].
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.