Sentence:  In the last few <WSD>years</WSD> , the application of chromatographic and other modern techniques to the problem of isolating TSH has led to further purification ( Bates and Condliffe , 1960 ; Pierce , Carsten and Wynston , 1960 ) . 
Meaning of the word marked with <WSD> tags:  a period of time containing 365 (or 366) days