Original sentence: A sibling language of Greek within Indo-European,  Macedonian and Greek forming two subbranches of a Greco-Macedonian subgroup within Indo-European  (sometimes called "Hellenic"),  suggested by  Joseph (2001), Georgiev (1966), Hamp & Adams (2013),
Edited sentence: A sibling language of Greek within Indo-European,  Macedonian and Greek forming two subbranches of a Greco-Macedonian subgroup within Indo-European  (sometimes called "Hellenic"),  suggested by  Joseph (2001) and Hamp & Adams (2013),