Mishnah Taharos 2:6: Non-sacred foods of a second degree render non-sacred liquids impure, and invalidate [foods] for those who eat terumah. Terumah of a third degree renders sanctified liquids impure, and invalidates [foods] for those who eat sanctified foods, [and this applies] when they were prepared with the purity stringency of sanctified things. But if they were prepared [only] with the purity stringency of terumah, it [terumah of a third degree] renders, with regard to sanctified foods, two impure [i.e. creates, upon contact, a first degree impurity and, in turn, a second degree impurity] and invalidates one [in turn, to be a third degree level of impurity, but not a fourth degree; this is because foods prepared with the purity stringency of terumah are still impure at a first degree level with regard to sanctified foods, but they do not retain a fourth degree impurity, since terumah cannot retain a fourth degree of impurity].

הַשֵּׁנִי שֶׁבְּחֻלִּין, מְטַמֵּא מַשְׁקֵה חֻלִּין, וּפוֹסֵל לְאֳכָלֵי תְרוּמָה. הַשְּׁלִישִׁי שֶׁבַּתְּרוּמָה, מְטַמֵּא מַשְׁקֵה קֹדֶשׁ, וּפוֹסֵל לְאֳכָלֵי קֹדֶשׁ שֶׁנַּעֲשׂוּ לְטָהֳרַת הַקֹּדֶשׁ. אֲבָל אִם נַעֲשׂוּ לְטָהֳרַת תְּרוּמָה, מְטַמֵּא שְׁנַיִם וּפוֹסֵל אֶחָד בַּקֹּדֶשׁ:

Mishnah Taharos 2:7: Rabbi Eliezer says: The three of them are the same. First degree sanctified foods, terumah foods, and non-sanctified foods, [all] render two impure and invalidate one with regard to sanctified foods; [they all] render one impure and invalidate one with regard to terumah; and they invalidate non-sanctified foods [by rendering them impure]. The second degree [foods] for all [of these three categories], render one impure and invalidate one with regard to sanctified foods, render non-sanctified liquids impure, and invalidate [foods, by rendering them impure] for those who eat terumah. The third degree [foods] for all [of these three categories], render sanctified liquids impure, and invalidate [foods] for those who eat sanctified foods.

רַבִּי אֱלִיעֶזֶר אוֹמֵר, שְׁלָשְׁתָּן שָׁוִין. הָאֶחָד שֶׁבַּקֹּדֶשׁ וְשֶׁבַּתְּרוּמָה וְשֶׁבְּחֻלִּין, מְטַמֵּא שְׁנַיִם וּפוֹסֵל אֶחָד בַּקֹּדֶשׁ, מְטַמֵּא אֶחָד וּפוֹסֵל אֶחָד בַּתְּרוּמָה, וּפוֹסֵל אֶת הַחֻלִּין. הַשֵּׁנִי שֶׁבְּכֻלָּן, מְטַמֵּא אֶחָד וּפוֹסֵל אֶחָד בַּקֹּדֶשׁ, וּמְטַמֵּא מַשְׁקֵה חֻלִּין, וּפוֹסֵל לְאֳכָלֵי תְרוּמָה. הַשְּׁלִישִׁי שֶׁבְּכֻלָּן, מְטַמֵּא מַשְׁקֵה קֹדֶשׁ וּפוֹסֵל לְאֳכָלֵי קֹדֶשׁ: