 
 <prompt> Which one be di most reliable source on cubism? Based on di previous question, write one context wey contain di answer. E fit be 1 - 20 sentences. Context: <response>: ```Di historical study of Cubism start for late 1920s, based on small data sources like di opinions of Guillaume Apollinaire. E come rely well well on Daniel-Henry Kahnweiler book Der Weg zum Kubismus (wey dem publish for 1920), wey focus on di developments of Picasso, Braque, Léger, and Gris. Di terms "analytical" and "synthetic" wey come out later don dey widely accepted since mid-1930s. Both terms na historical impositions wey happen after di facts wey dem identify. No be so dem call di phases when di corresponding works dey created. "If Kahnweiler see Cubism as Picasso and Braque," Daniel Robbins write, "our only fault na to dey subject other Cubists' works to di strictness of dat limited definition."``` 