Both of Charles Hajdamach's offerings should probably be at the top of anyone's list............... 'British Glass 1800 - 1914' is one, and the other is his '20th Century Glass' ........ think they're both Antique Collectors Club volumes, and both very heavy and difficult to read in the bath.
As you'd expect from a top flight author, the text is superb and probably better than any comparably related volume.
for a general dip into (mostly) modern Scandi Glass then the two Schiffer plublications form Pina & Vigier are worthwhile ........... 'Fire & Sea' and the other is 'Smoke & Ice'.
If you don't have them, Miller's '20th Century Glass' by Andy McConnell is very good for general modern glass from a variety of sources, and Judith Millers' own input via Dorling Kindersley - '20th-CENTURY GLASS which, although it has the same title provides a very different take on makers and types of glass.
the Millers books tend to be good on pix and short on text - but since we need ids based on comparisons, then pix are equally as important as text.
In addition to her W/Fs volume, Leslie Jackson did '20th Century Factory Glass' - good on both pix and text - covers mostly European, Scandi and some States.
Two pocket sized offerings are ................ 'glass fact file a-z' from Ivo Haanstra - a dictionary format measuring 7.75" x 4", which suppose would go into some pockets, but not actually tried.
Of identical size is another very reliable quickie guide from Mark West - 'GLASS Antiques Checklist' - good but small pix and covers essential points and questions for most popular areas of glass that we're likely to see - if not always able to buy. Obviously, the text is reduced in volume but what there is does make for a very useful booklet.
Am sure others will be able to suggest more titles. There is one thing worse than not having enough books ........................ which is having too many ......... you can spend hours trawling for some snippet that you know is there but can't remember where it is in the ninety odd books you have.
Best of luck.