"PHC80-P-37.""Issued February 1981"--P. [1].At head of title: Preliminary reports.Caption title.Mode of access: Internet
"PHC80-P-19.""Issued January 1981."At head of title: Preliminary reports.Caption title.Mode of acces...
"PHC80-P-35.""Issued February 1981."At head of title: Preliminary reports.Caption title.Mode of acce...
"PHC80-P-48.""Issued February 1981"--P. [1].At head of title: Preliminary reports.Caption title.Mode...
"PHC80-P-39.""Issued January 1981."At head of title: Preliminary reports.Caption title.Mode of acces...
"PHC80-P-34.""Issued February 1981."At head of title: Preliminary reports.Caption title.Mode of acce...
"PHC80-P-51.""Issued February 1981"--P. [1].At head of title: Preliminary reports.Caption title.Mode...
"PHC80-P-9"--P. 1."Issued November 1980"--P. 1.At head of title: Preliminary reports.Caption title.M...
"PHC80-P-6.""Issued February 1981"--P. [1].At head of title: Preliminary reports.Caption title.Mode ...
"PHC80-P-38.""Issued January 1981."At head of title: Preliminary reports.Caption title.Mode of acces...
"PHC80-P-18.""Issued February 1981."At head of title: Preliminary reports.Caption title.Mode of acce...
"PHC80-P-8.""Issued January 1981."At head of title: Preliminary reports.Caption title.Mode of access...
"PHC80-P-25.""Issued February 1981."At head of title: Preliminary reports.Caption title.Mode of acce...
"PHC80-P-26.""Issued February 1981"--P. [1].At head of title: Preliminary reports.Caption title.Mode...
"PHC80-P-29.""Issued February 1981."At head of title: Preliminary reports.Caption title.Mode of acce...
"PHC80-P-44.""Issued January 1981"--P. [1].At head of title: Preliminary reports.Caption title.Mode ...
"PHC80-P-19.""Issued January 1981."At head of title: Preliminary reports.Caption title.Mode of acces...
"PHC80-P-35.""Issued February 1981."At head of title: Preliminary reports.Caption title.Mode of acce...
"PHC80-P-48.""Issued February 1981"--P. [1].At head of title: Preliminary reports.Caption title.Mode...
"PHC80-P-39.""Issued January 1981."At head of title: Preliminary reports.Caption title.Mode of acces...
"PHC80-P-34.""Issued February 1981."At head of title: Preliminary reports.Caption title.Mode of acce...
"PHC80-P-51.""Issued February 1981"--P. [1].At head of title: Preliminary reports.Caption title.Mode...
"PHC80-P-9"--P. 1."Issued November 1980"--P. 1.At head of title: Preliminary reports.Caption title.M...
"PHC80-P-6.""Issued February 1981"--P. [1].At head of title: Preliminary reports.Caption title.Mode ...
"PHC80-P-38.""Issued January 1981."At head of title: Preliminary reports.Caption title.Mode of acces...
"PHC80-P-18.""Issued February 1981."At head of title: Preliminary reports.Caption title.Mode of acce...
"PHC80-P-8.""Issued January 1981."At head of title: Preliminary reports.Caption title.Mode of access...
"PHC80-P-25.""Issued February 1981."At head of title: Preliminary reports.Caption title.Mode of acce...
"PHC80-P-26.""Issued February 1981"--P. [1].At head of title: Preliminary reports.Caption title.Mode...
"PHC80-P-29.""Issued February 1981."At head of title: Preliminary reports.Caption title.Mode of acce...
"PHC80-P-44.""Issued January 1981"--P. [1].At head of title: Preliminary reports.Caption title.Mode ...
"PHC80-P-19.""Issued January 1981."At head of title: Preliminary reports.Caption title.Mode of acces...
"PHC80-P-35.""Issued February 1981."At head of title: Preliminary reports.Caption title.Mode of acce...
"PHC80-P-48.""Issued February 1981"--P. [1].At head of title: Preliminary reports.Caption title.Mode...