Re: bolt-in circuit breakers
Another No and Yes answer.
No you will not find a code article that says breakers must be bolt in.
Hoverer you will find a code article
"110.9 Interrupting Rating" that basically says the breakers have to be able to handle the fault current available.
In many commercial locations the available fault current will be above the ratings of "plug in breakers" so in a round about way bolt on breakers may be required to meet 110.9.