In her analysis / review / overview / critique of X, Bertram [2] questions the need for …
In his introduction to / seminal article on / investigation into X, Schneider [3] shows that …
Dee [4] developed / reported on a new method for X and concluded that …
Southern’s group [5] calls into question some past assumptions / hypotheses / theories about X.
Burgess [6], an authority on X, notes / mentions / highlights / states / affirms that …
She questions / wonders / considers / investigates whether [or not] X can …
He traces the advances in / development of / history of / evolution of X They draw our attention to / focus on X.
They make / draw a distinction between …
He claims / argues / maintains / suggests / points out / underlines that … She concludes / comes to the conclusion / reaches the conclusion that …
She lists / outlines / describes / provides several reasons for …
Her theory / solution / proposal / method / approach is based on …