Arukh HaShulchan, Orach Chaim 273:6ערוך השולחן, אורח חיים ער״ג:ו׳
...
Mishnah Berurah 213:3משנה ברורה רי״ג:ג׳
...
Shulchan Arukh, Orach Chayim 213:1שולחן ערוך, אורח חיים רי״ג:א׳
On all fruits and other foods - aside from bread and wine - if there are two or more foods, then the blessing of one covers the other even without reclining. Sitting, however, is required specifically with bread or wine that does require reclining. But, for us, that's sitting just as like the type of reclining they used to do in tannaitic times. And, according to this, for us, since we do not recline when we eat, there's no differentiation between eating bread and drinking wine versus other food or beverages for consumption since, with regards to sitting, even with bread and wine, one blesses for all of them and not with sitting with other consumables also everybody blesses for oneself. But we say that one blesses for all of them with all other things aside from bread, that's with regards to the pre-consumption blessing, but with the post-consumption blessing, we do need to differentiate and everybody blesses for oneself since there is no call to blessing for fruits. GLOSS: And there are some who say that with all food and drink aside from bread and wine that reclining does not help, and this is similarly the case with our sitting. And, therefore, we are accustomed nowadays with fruits, that everyone who is at the meal blesses upon the fruits for themselves.
Mishnah Berurah 250:3משנה ברורה ר״נ:ג׳
...
Mishnah Berurah 677:12משנה ברורה תער״ז:י״ב
...
Haamek Sheilah on Sheiltot d'Rav Achai Gaon 169:1:1העמק שאלה על שאילתות דרב אחאי גאון קס״ט:א׳:א׳
...
Biur Halacha 250:1:2ביאור הלכה ר״נ:א׳:ב׳
...
Haamek Sheilah on Sheiltot d'Rav Achai Gaon 165:1:1העמק שאלה על שאילתות דרב אחאי גאון קס״ה:א׳:א׳
...
Mishnah Berurah 453:41משנה ברורה תנ״ג:מ״א
...
Mishnah Berurah 432:8משנה ברורה תל״ב:ח׳
...
Arukh HaShulchan, Orach Chaim 460:4ערוך השולחן, אורח חיים ת״ס:ד׳
...
Arukh HaShulchan, Orach Chaim 432:4ערוך השולחן, אורח חיים תל״ב:ד׳
...