Reference for Bikkurim 2:5
תְּרוּמַת מַעֲשֵׂר שָׁוָה לַבִּכּוּרִים בִּשְׁתֵּי דְרָכִים, וְלַתְּרוּמָה בִּשְׁתֵּי דְרָכִים. נִטֶּלֶת מִן הַטָּהוֹר עַל הַטָּמֵא, וְשֶׁלֹּא מִן הַמֻּקָּף, כַּבִּכּוּרִים. וְאוֹסֶרֶת אֶת הַגֹּרֶן, וְיֶשׁ לָהּ שִׁעוּר, כַּתְּרוּמָה:
<i>Terumat Ma’aser</i> [a tenth of the tithe given to a Levite which must, in turn, be given to a <i>Kohen</i> and which becomes holy upon separation, and can only be consumed by <i>Kohanim</i> or their household] is similar to <i>Bikkurim</i> in two ways, and to <i>Terumah</i> in two ways. It may be taken from pure produce to [permit] impure produce [to be eaten], and [it may be taken] from produce that is not in proximity [to the produce it is making permissible], like <i>Bikkurim</i>. And it makes what is on the threshing floor forbidden [before it is separated], and it has a required amount, like <i>Terumah</i>.