This was published jointly with Khinchin and contains the 'three series' theorem as well as results on inequalities of partial sums of random variables which would become the basis for martingale inequalities and the stochastic calculus.
Ito ay nai-publish na sama-sama sa Khinchin at naglalaman ng 'tatlong serye' teorama pati na rin ang mga resulta sa inequalities ng bahagyang sums ng random na mga variable na kung saan ay maging ang batayan para sa matingeil inequalities at ang stochastic calculus.