What is the meaning of Ap.?

Abbreviation of apud. Used in scholarly works to cite a reference at second hand

Abbreviation of a podobně: and so on

Abbreviation of aamupäivällä (before noon, in the morning, ante meridiem); am, a.m.

Abbreviation of après.

Abbreviation of apartament (apartment).

Abbreviation of a podobne.

Source: wiktionary.org