t 49.898 

'r~rrell),Jr J rl_-.l,Lt.CoL: The '7illiams System 
01 classiftcationJ catalogtiing, i:1dexing, ftl in~J and 
car~ 0 f maps as adopted for the General Ci taff ~fap 
Colleetion.l'Vashin~ton< 2.~d. -'Vashil1,~t,on:cVQr Dep;
lrt:~~nt 1080. 2fi S. ,1 1'.1. ,I 1. P; . J 4 TIeiL J 2 iml. 
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