TY - PROGRESS IN GEOGRAPHY A1 - T1 - Y1 - 1991-12-24 00:00:00.0 JF - PROGRESS IN GEOGRAPHY JO - PROGRESS IN GEOGRAPHY SP - 64 EP - 65 VL - 10 IS - 4 UR - {https://www.progressingeography.com/EN/10.11820/dlkxjz.1991.04.016} N1 - 10.11820/dlkxjz.1991.04.016 ER -