Hirasawa Go: Selfadjoint operators and symmetric operators. In: Acta scientiarum mathematicarum, (82) 3-4. pp. 529-543. (2016)
Hirasawa Go: A topology for semiclosed operators in a Hilbert space. In: Acta scientiarum mathematicarum, (73) 1-2. pp. 271-282. (2007)
Hirasawa Go: Extremal positive selfadjoint extensions of a positive symmetric quotient. In: Acta scientiarum mathematicarum, (65) 1-2. pp. 203-216. (1999)