I made a vba macro for excel in windows to get several DOIs from plain text citations via crossref.
With the DOIs, you can get all bibtex formatted citations with R.
1. Download excel file with macro
2. Put your plain text citations in column A, modify slightly the numbers in columns F and H to get correctly the title in column K.
3. Press Ctrl A, and wait ca. 5 sec per citation.
(in order to use again, restore formulas with the backup sheet)
4. Locate your .csv file with DOIs saved, or save it again manually from sheet2
5. Use something like this to query your DOIs in R
library(RefManageR)
setwd("/your/folder/") # set the folder where the .csv file is
list.files(getwd()) # be sure your .csv file is there
doi<-read.csv("dois.csv", header=FALSE) # pass the file info to the doi object
# get a new .bib file with formatted references
GetBibEntryWithDOI(unlist(doi), temp.file = ("mycitations.bib"), delete.file = FALSE)
# write a .csv
bib<-ReadBib("mycitations.bib")
dfbib<-as.data.frame(bib)
write.csv(dfbib,"table.csv")