EVOLUTION OF OVULE

[31] Eames A.J, 1961, MORPHOLOGY ANGIOSPER, P87

[32] EMBERGER L, 1944, PLANTS FOSSILES DANS

[33] Florin R., 1951, ACTA HORI BERGIANI, V15, P285

[34] Florin R, 1950, ACTA HORTI BERGIANI, V15, P111

[35] GORDON W. T., 1941, TRANS ROY SOC EDINBURGH, V60, P427

[36] Pennsylvanian flora of Illinois as revealed in coal balls II [J]. BOTANICAL GAZETTE, 1935, 97 : 156 - 168

[37] THE GENUS STEPHANOSPERMUM IN AMERICAN COAL BALLS [J]. BOTANICAL GAZETTE, 1954, 115 (04): : 346 - 360

[38] Halle T.G., 1933, KUNGL SVENSKA VETENS, V12, P1

[39] HALLE TG, 1929, SVENSKA VETENSK AKAD, V6, P1

[40] HALLE TG, 1937, 2 C AV ET STR CARB C, V1, P227

[31] Eames A.J, 1961, MORPHOLOGY ANGIOSPER, P87

[32] EMBERGER L, 1944, PLANTS FOSSILES DANS

[33] Florin R., 1951, ACTA HORI BERGIANI, V15, P285

[34] Florin R, 1950, ACTA HORTI BERGIANI, V15, P111

[35] GORDON W. T., 1941, TRANS ROY SOC EDINBURGH, V60, P427

[36] Pennsylvanian flora of Illinois as revealed in coal balls II [J]. BOTANICAL GAZETTE, 1935, 97 : 156 - 168

[37] THE GENUS STEPHANOSPERMUM IN AMERICAN COAL BALLS [J]. BOTANICAL GAZETTE, 1954, 115 (04): : 346 - 360

[38] Halle T.G., 1933, KUNGL SVENSKA VETENS, V12, P1

[39] HALLE TG, 1929, SVENSKA VETENSK AKAD, V6, P1

[40] HALLE TG, 1937, 2 C AV ET STR CARB C, V1, P227