Virgil's biographical tradition is thought to depend on a lost biography by Varius, Virgil's editor, which was incorporated into the biography by Suetonius and the commentaries of Servius and Donatus, the two great commentators on Virgil's poetry. Although the commentaries no doubt record much factual information about Virgil, some of their evidence can be shown to rely on inferences made from his poetry and allegorizing; thus, Virgil's biographical tradition remains problematic.
Is Virgil's biographical tradition easily researched or is it problematic?
problematic

Congo is located in the central-western part of sub-Saharan Africa, along the Equator, lying between latitudes 4N and 5S, and longitudes 11 and 19E. To the south and east of it is the Democratic Republic of Congo. It is also bounded by Gabon to the west, Cameroon and the Central African Republic to the north, and Cabinda (Angola) to the southwest. It has a short coast on the Atlantic Ocean.
What is another name for Cabinda?
Angola

Catalan sociolinguistics studies the situation of Catalan in the world and the different varieties that this language presents. It is a subdiscipline of Catalan philology and other affine studies and has as an objective to analyse the relation between the Catalan language, the speakers and the close reality (including the one of other languages in contact).
What is this a subdiscipline of?
Catalan philology