International classification of hard coals by type /
- Geneva : United Nations, 1956.
- 52 p. : illus., diagrs., tables; 28 cm.
- [United Nations. Document] E/ECE/247, E/ECE/Coal/110 .
- United Nations. Document. French ed. E/ECE/247 [etc.] .
- [Document] (United Nations) ; E/ECE/247 [etc.] .
"United Nations publication. Sales no. : 1956.II.E.4."
57001666
Coal--Grading.
JX1977 / .A2 E/ECE/247, etc.
662.62 / UNI
"United Nations publication. Sales no. : 1956.II.E.4."
57001666
Coal--Grading.
JX1977 / .A2 E/ECE/247, etc.
662.62 / UNI