Liu Weimin, Huang Zhaozhi, Pan Bingzhi, Chen Lunyuan. STUDY OF STRESS INTENSITY FACTOR KI FOR INTERNAL SURFACE CRACKS IN PRESSURIZED THIN SPHERICAL SHELL USING FROZEN STRESS PHOTO-ELASTIC METHOD[J]. Editorial office of ACTA PETROLEI SINICA, 1988, 9(2): 92-98.