请问大神们stata里面怎么下载treagtreg heckman boost命令呢？我已经用了. ssc install heckmanssc install: "heckman" not found at SSC, type -findit heckman-
(To find all packages at SSC that start with h, type -ssc describe h-)
r(601);
. ssc install boost
ssc install: "boost" not found at SSC, type -findit boost-
(To find all packages at SSC that start with b, type -ssc describe b-)
r(601);

都是出现的这种结果，也用了 findit ,也是未安装成功，请问大家的这几个命令是怎么下载安装的呢？