International classification of hard coals by type
By: prepared by the Secretariat. Classification internationale des houilles par nature.
Series: [United Nations. Document] E/ECE/247, E/ECE/Coal/110; [Document] (United Nations) ;; E/ECE/247 [etc.]
Publisher: United Nations
Published: 1956
Place of publication: Geneva
Language: eng
Number of pages: 52
Subjects: Coal -- Grading.
Other titles: Classification internationale des houilles par nature.
Notes: "United Nations publication. Sales no. : 1956.II.E.4."