@inbook{Parker2019,
author = {Parker, C. and Scott, S. and Geddes, A.},
title= {Snowball sampling},
year = {2019},
doi = {10.4135/9781526421036831710},
editor = {Atkinson, P.},
editor = {Delamont, S.},
editor = {Vernat, A.},
editor = {Sakshaug, J. W.},
editor = {Williams, R. A.},
booktitle = {SAGE Research Methods Foundations},
address = {Thousand Oaks},
publisher = {SAGE Publications Ltd},
}