I don't think it refers to a particular text, but is primarily shit I've picked up either through osmosis, my own research into Soviet history, or both. It essentially boils down to:

• Lenin essentially gambled everything on the October Revolution setting off the spark of revolution across all of Europe, especially Germany. This uniformly failed across the board.
• With the failure of revolution in Europe, the USSR was not only diplomatically isolated but also entirely materially unprepared for establishing a socialist revolution. Worse, the Russian Civil War physically annihilated the Russian proletariat, killing the vibrant embryos of soviet democracy and leaving the VKP(b) the only remaining coherent institution
• Furthermore, the Russian Revolution was a dual, parallel revolution - the proletarian revolution in the cities and the peasant revolution on the land. This entrenched a fragile and begrudging alliance between the party/proletariat and the peasantry (town and country) that was inevitably going to result in a confrontation between the two, as they had contradictory visions of what "socialism" meant.
• Stalin came to power through skillful politicking and manipulation of the party apparatus and aggressively cleared the board of any rivals. With the USSR isolated, backward, and unstable - the NEP facing crisis and tensions between town and country/center and periphery mounting - Stalin decided the best course of action forward was essentially appropriating the crash industrialization program of the former Left Opposition. This entailed an extremely violent and rapid period of primitive accumulation through brutal state repression, an effective declaration of war on the peasantry in the countryside to enact forced collectivization to fuel the industrialization program. Famine and terror inevitably ensued as a result.
• Whether or not Stalin's choices were necessary will be a riddle for the ages, because he was objectively correct about Russia needing to "catch up in ten years or the capitalist West will crush us", as the Nazi invasion occurred ten years after he made that speech. Twenty-seven million Soviets died to that onslaught, which also laid waste to the USSR's prime industrial and agricultural regions.
• By the end of WWII, the collapse of relations with the USA, and the onset of Cold War ossification, the USSR was so hopelessly far behind the West that catching up was impossible. The Sino-Soviet Split was the final nail in the coffin as it allowed the USA to triangulate the PRC against the USSR, and the revolution in the USSR was slowly suffocated over the course of forty years.

I'm actually much more charitable toward Stalin than most self-identified left-communists, who largely despise him and share the Trotskyist position that he was the "Soviet Thermidor".