3 literature references for Isopterygium rubellum Sakurai, 1940:

Author: Iwatsuki, Z.
Year: 1991
Title:
Source: Cat. Mosses Japan
Author: Crosby, M. R. and others - INSUFFICIENT
Year: 1999
Title: INSUFFICIENTLY known because not REVISED since its pre-1963 publication; that is to say we have no more information about the species than Index Muscorum; merely relisted without additional specimens in a checklist since 1963; may have been treated in
Source: Checklist Mosses
Author: Sakurai
Year: 1940
Title:
Source: Bot. Mag. (Tokyo)