'40 Tahun PKI', compiled by the PKI History Institute (Lembaga Sejarah PKI) for the party's 40th anniversary, Yayasan Pembaruan, Jakarta 1960, following D.N. Aidit's 'Lahirnya PKI dan perkembangannya'. A party-line history from the 1920 founding through the 1926 uprising, Japanese occupation, revolution and the VI Cong
Ipong Jazimah's 2016 biographical sketch of S.K. Trimurti (1912-2008): journalist, labour minister, Gerwis co-founder, Petisi 50 signatory. Pages 50-51 cover Gerwis's founding; relies on a few secondary sources.
Tempo.co explainer (29 Sept 2021) on organisations 'considered affiliated' with the PKI: Gerwani, Lekra, SOBSI, Pemuda Rakjat. It states, citing Wieringa, that Gerwis became Gerwani at its 1954 second congress, electing PKI member Umi Sardjono as chair. Short, background-level.