1966. Fourth Edition. 192 pages. Pictorial dust jacket over blue cloth with gilt lettering. Minor foxing and tanning to pages. Noticeably more prominent to text block edges, pastedowns and free endpapers. Binding remains firm. Boards have minor corner bumping and edgewear with mild tanning and scuffing overall. Spine has slightly heavier tanning with soft crushing to ends. Lettering remains bright and clear. Unclipped dust jacket with minor rubbing, chipping and tearing to edges. Moderate tanning and scuffing overall.