Guide to the Poisonous Plants and Weed Seeds of Canada and the Northern United StatesRobert Boyd Thomson, Harold Boyd Sifton · First published 1922Open the Tome
Resin canals in the Canadian spruce (Picea canadensis (Mill.) B.S.P.)Robert Boyd Thomson, Harold Boyd Sifton · First published 1925Open the Tome
Some features in the anatomy of the Cycads and their bearing on the phylogeny of the conifersHarold Boyd Sifton · First published 1915Open the Tome
Some characters of Xylem tissue in Cycads and The bar of Sanio and primordial pit in the GymnospermsHarold Boyd Sifton · First published 1900Open the Tome
