Cómo extraer oraciones que contienen marcas de citas con R

Por ejemplo, tengo String:

string = "The present paper describes an analysis of data from a cohort study of occupational stress in the Royal Navy (Bridger et al., 2010). Data from 2008 Phase III and 2010 Phase V of the survey were analysed to determine whether (cumulative) scores on the General Health Questionnaire (Goldberg and Williams, 1988) and the CFQ (Broadbent et al., 1982), were related to the occurrence of accidents over a three-year period (2007–2010)"

El resultado debería ser así:

"The present paper describes an analysis of data from a cohort study of occupational stress in the Royal Navy (Bridger et al., 2010)."

¡por favor, ayúdame

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