dip into
Investigate superficially, as in He began to dip into Chaucer, or She's just dipping into psychology. This expression alludes to plunging briefly into a liquid. [Late 1600s]
Withdraw something in small amounts, usually money, as in I'll have to dip into my savings. This usage employs dip into in the sense of plunging one's hand or a ladle into a pot, water, or the like for the purpose of taking something out. [Early 1800s]