A couple of years ago I got really frustrated because I was spending a whole lot of time thumbing through some of my books and then researching yarns online to find out first) the weight of the yarn used in the book and then second) an acceptable substitute. I started making notes and before long my book was crammed with little post its and odd scraps of paper. Finally sat down one day and made a spreadsheet of my research. So, for what it's worth, I am going to link to my spreadsheets that I made for the Folk Shawls book and Victorian Lace Today. And please remember that I am human and make mistakes so please verify anything before you take it to the bank....Look for the links in my sidebar. The spreadsheets are stored on google documents and you should be able to print or download them from there.
Enjoy and let me know if you find them helpful!