^Singh, Mahendra Prasad (1981). Split in a Predominant Party: The Indian National Congress in 1969. Abhinav publications. p. 69. ISBN9788170171409. Retrieved 18 July 2024. The support for the decision was more solid among the left-wing parties; in addition to the Communist Party of India(CPI), Communist Party of India-Marxist(CPI-M), Samyukta Socialist Party(SSP), and Praja Socialist Party(PSP)...
^ abBrass, Paul R. (2014). An Indian Political Life: Charan Singh and Congress Politics, 1967 to 1987 - Vol.3 (The Politics of Northern India). Sage India. p. 156. ISBN978-9351500322.