1321
The complete structure assignments were obtained by means of ( 1 ) H and ( 13 ) C NMR spectra .
 ( 1 ) H, ( 13 ) C
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 ( 1 ) H, ( 13 ) C