LEGO 6894: Invader | Brickset: LEGO set guide and database
6894 Invader - Brickipedia, the LEGO Wiki
LEGO 6894 Invader Set Parts Inventory and Instructions - LEGO Reference Guide
LEGO 6894 Invader Instructions, Space
Space Theme Sets - LEGO 6894 Invader Original Vintage Blacktron Space Ship Set
After digging through a box of gifted LEGO for hours and only one piece of the instruction booklet left, I finally completed this. 6894 Blacktron Invader : r/lego