Willem Mauritius van Eldik

Willem Mauritius van Eldik (sometimes spelled as Van Eldick), also known as Sastrodihardjo (June 10, 1882 – May 5, 1954) was a music teacher who was the teacher of Wage Rudolf Supratman. Apart from his music teacher, W. M. van Eldik was also WR Supratman's brother-in-law.

Biography
W. R. Supratman's music teacher, Willem Mauritius van Eldik was born in Bendosari Village, Ngantru District, Tulungagung. Van Eldik is a child of a Dutch (Indo) descent who lives in Darungan hamlet, while his mother is a native from Ngantru. Van Eldik also had a sibling named M. B. F. Van Eldik, who is buried next to him. Apart from working as a music teacher, he is also a Sergeant Instructor for the Royal Netherlands East Indies Army (KNIL) Battalion XIX who previously served in Surabaya.

W. M. van Eldik gave a violin as a gift on WR Supratman's 17th birthday. With this violin, Supratman, who received his knowledge of musical arts from van Eldik, created the national anthem Indonesia Raya.

Death
He died on May 5, 1954. Sastrodiharjo was originally buried in the “bong londo” or Dutch cemetery, south of the current grave.

Then the grave was moved to the Ngujang Village TPU location where it remains today.

Family
Sastrodihardjo married Rukiyem first. Rukiyem is the older sister of WR Supratman.

From this marriage Sastrodihardjo had no children.

He then married Tumijah. From this marriage four children were born, namely Nanik Yatrini, Hani Purwanto, Yunarso and Subartono.