Circular - Pennsylvania State University, College of Agriculture, Extension Service.

v.1-41; v.43-70(1915-1917); v.45-73; v.71-95(1918-1922); v.74-100 (W/O 79,92); v.96-119(1922-1928); v.120-150(1929-1934); v.120 (Rev.)(1931); v.112 (Rev.)(1943); v.89 (3rd Rev.)(1947); v.151-195(1935-1937); v.196-233(1938-1941); v.234-269(1942-1944); v.270-298(1944-1946); v.299-325(1946-1949); v.326-360(1949-1950); v.361-400(1950-1952); v.401-440(1952-1954); v.347 (Rev.)(1955); v.441-470(1954-1957); v.471-500(1958-1960); v.501-525(1961-1963); v.526-540(1965-1967); v.541-560 (W/O 554)(1968-1969); v.331 (Rev.)(1988); v.359 (Rev.)(1988); v.360 (Rev.)(1988)