TY - JOUR
T1 - Preface: Special Issue Dedicated to Professor Roger Penrose's 90th Birthday
JO - Communications in Mathematical Research 
VL - 4
SP - i
EP - ii
PY - 2021
DA - 2021/08
SN - 37
DO - http://doi.org/10.4208/cmr.2021.v37n4.preface
UR - https://global-sci.org/intro/article_detail/cmr/19436.html
KW - 
AB -