1971. Sixth Revised Edition. 262 pages. No dust jacket. Blue cloth. Minor foxing and tanning to pages. More prominent to text block edges, pastedowns and free endpapers. Occasional annotations, underlining and marginalia in pen; text remains unaffected. Binding remains firm. Boards have minor corner bumping and edgewear with mild mottling, tanning and scuffing overall. Spine has similar tanning with soft crushing to ends.