Butterick's instruction sheets for the period, which they called The Deltor, are very good. This one in particular is very detailed.
Here are some things to note in The Deltor:
Direction to make flat felled seams. Note that the instructions for the Red Cross relief pattern for the matinee blouse called for flat felled seams and recommended that the maker examine a man's shirt to see what this looked like.
Explicit instructions to interline (today we would generally say interface) the cuffs and collar with muslin. The lack of interfacing in vintage sewing for women's clothes has always been a puzzle to me. My observation has been that vintage sewing books call for interlining only for men's shirts and for tailored garments. Clothing drapes differently when there isn't any interfacing in collars, cuffs, and facings; this is something that working with vintage patterns teaches us.
Instructions to make gussets at the bottoms of the side seams. This technique for strengthening the bottom of a shirt is centuries old. You can see what it looks like in real life on this shirt that I recently finished (Scroll down, it's in the last few photos.)
The fabrics recommended for this shirt are flannel, khaki, cotton shirtings, pongee, and cheviot.
Cheviot shirting, in case you were wondering, has two definitions: "1. A heavy twilled cotton shirting made with heavy yarn. The pattern is usually a small dobby design, single warp stripe, or double warp rib, in blue or brown on white ground. Formerly popular for inexpensive work shirts. 2. A British term for a soft finish, high quality cotton shirting woven with medium count combed yarns in square constructions, in either a plain or basket weave." (Fairchild's Dictionary of Textiles, 4th printing, 1975) It's interesting how different these two definitions are.
Here's the back of the envelope; note the very cool purple stamp B.(utterick)P.(attern)Co.(mpany) in the upper right corner. This may be the only Butterick pattern I own that has this stamp; I have no idea what distinguishes this pattern from any of the other Butterick patterns I have.