1905 Cover fr 2c,20c pmk CO , Bolivia to Washington DC b/s NY
1909 Cover fr 2c green, 20c black & lilac pmk Potosi - to Washington, DC - b/s La Paz & Callao
1916 20c blk & purple BISECT on cover pmk TUPIZA-2.8.26 to La Paz [arr 7.8.16 cds] - Scarce!
1944 Horiz pair 60c rose - RH stamp BISECT vert. tied to grey cover pmk 'La Paz - 22 X.44' to Buenos Aires. [Back of cover List of Nat'l Textbooks]