Editorial style

I am looking at "Grammar, Punctuation, and Capitalization, A Handbook for Technical Writers and Editors", published by NASA. It's like a Strunk & White Elements of Style for technical writers. (The 1918 publication of Elements of Style is available at Bartleby) Wondering what other guides people follow if they don't have a content/editorial person in their group.

For citing references, I've used the Chicago Manual of Style in the past, although I don't own a copy now, and APA style for research writing.